diff --git a/lib/language_util.dart b/lib/language_util.dart
index a43d68c5..ec9fb41f 100644
--- a/lib/language_util.dart
+++ b/lib/language_util.dart
@@ -47,7 +47,7 @@ enum _AppLanguageEnum {
 
 AppLanguage _getSelectedLanguage() {
   try {
-    final lang = Pref.inst().getLanguageOr(0);
+    final lang = Pref().getLanguageOr(0);
     return supportedLanguages[lang]!;
   } catch (_) {
     return supportedLanguages[_AppLanguageEnum.systemDefault.index]!;
diff --git a/lib/main.dart b/lib/main.dart
index 13abeafd..d2c30c8b 100644
--- a/lib/main.dart
+++ b/lib/main.dart
@@ -75,14 +75,14 @@ void _initLog() {
 }
 
 Future<void> _initPref() async {
-  await Pref.init();
-  if (Pref.inst().getLastVersion() == null) {
-    if (Pref.inst().getSetupProgress() == null) {
+  await Pref().init();
+  if (Pref().getLastVersion() == null) {
+    if (Pref().getSetupProgress() == null) {
       // new install
-      await Pref.inst().setLastVersion(k.version);
+      await Pref().setLastVersion(k.version);
     } else {
       // v6 is the last version without saving the version number in pref
-      await Pref.inst().setLastVersion(6);
+      await Pref().setLastVersion(6);
     }
   }
 }
diff --git a/lib/metadata_task_manager.dart b/lib/metadata_task_manager.dart
index f0616113..f8ef072e 100644
--- a/lib/metadata_task_manager.dart
+++ b/lib/metadata_task_manager.dart
@@ -29,7 +29,7 @@ class MetadataTask {
         final op = UpdateMissingMetadata(fileRepo);
         await for (final _ in op(account,
             File(path: "${api_util.getWebdavRootUrlRelative(account)}/$r"))) {
-          if (!Pref.inst().isEnableExifOr()) {
+          if (!Pref().isEnableExifOr()) {
             _log.info("[call] EXIF disabled, task ending immaturely");
             op.stop();
             return;
@@ -76,7 +76,7 @@ class MetadataTaskManager {
 
   void _handleStream() async {
     await for (final task in _streamController.stream) {
-      if (Pref.inst().isEnableExifOr()) {
+      if (Pref().isEnableExifOr()) {
         _log.info("[_doTask] Executing task: $task");
         await task();
       } else {
diff --git a/lib/pref.dart b/lib/pref.dart
index f00c9893..892e6211 100644
--- a/lib/pref.dart
+++ b/lib/pref.dart
@@ -9,7 +9,11 @@ import 'package:nc_photos/use_case/compat/v32.dart';
 import 'package:shared_preferences/shared_preferences.dart';
 
 class Pref {
-  static Future<void> init() async {
+  factory Pref() => _inst;
+
+  Pref._();
+
+  Future<void> init() async {
     if (await CompatV32.isPrefNeedMigration()) {
       await CompatV32.migratePref();
     }
@@ -18,8 +22,6 @@ class Pref {
     });
   }
 
-  factory Pref.inst() => _inst;
-
   List<PrefAccount>? getAccounts2() {
     final jsonObjs = _pref.getStringList(_toKey(PrefKey.accounts2));
     return jsonObjs?.map((e) => PrefAccount.fromJson(jsonDecode(e))).toList();
@@ -138,8 +140,6 @@ class Pref {
   Future<bool> setLabEnableSharedAlbum(bool value) =>
       _setBool(PrefKey.labEnableSharedAlbum, value);
 
-  Pref._();
-
   Future<bool> _setBool(PrefKey key, bool value) async {
     return _onPostSet(await _pref.setBool(_toKey(key), value), key, value);
   }
@@ -207,7 +207,7 @@ class Pref {
     }
   }
 
-  static final _inst = Pref._();
+  static late final _inst = Pref._();
   late SharedPreferences _pref;
 }
 
@@ -277,16 +277,14 @@ enum PrefKey {
 extension PrefExtension on Pref {
   Account? getCurrentAccount() {
     try {
-      return Pref.inst()
-          .getAccounts2()![Pref.inst().getCurrentAccountIndex()!]
-          .account;
+      return Pref().getAccounts2()![Pref().getCurrentAccountIndex()!].account;
     } catch (_) {
       return null;
     }
   }
 
   AccountSettings getAccountSettings(Account account) {
-    return Pref.inst()
+    return Pref()
         .getAccounts2()!
         .firstWhere((element) => element.account == account)
         .settings;
diff --git a/lib/theme.dart b/lib/theme.dart
index 3b3e34d2..49b8ac4a 100644
--- a/lib/theme.dart
+++ b/lib/theme.dart
@@ -97,7 +97,7 @@ class AppTheme extends StatelessWidget {
   static ThemeData _buildDarkThemeData(BuildContext context, ThemeData theme) {
     final Color background;
     final Color popup;
-    if (Pref.inst().isUseBlackInDarkThemeOr(false)) {
+    if (Pref().isUseBlackInDarkThemeOr(false)) {
       background = Colors.black;
       popup = Colors.grey[900]!;
     } else {
diff --git a/lib/widget/account_picker_dialog.dart b/lib/widget/account_picker_dialog.dart
index a32d6017..7cda9a8f 100644
--- a/lib/widget/account_picker_dialog.dart
+++ b/lib/widget/account_picker_dialog.dart
@@ -29,7 +29,7 @@ class _AccountPickerDialogState extends State<AccountPickerDialog> {
   @override
   initState() {
     super.initState();
-    _accounts = Pref.inst().getAccounts2Or([]);
+    _accounts = Pref().getAccounts2Or([]);
   }
 
   @override
@@ -102,7 +102,7 @@ class _AccountPickerDialogState extends State<AccountPickerDialog> {
   }
 
   void _onItemPressed(PrefAccount account) {
-    Pref.inst().setCurrentAccountIndex(_accounts.indexOf(account));
+    Pref().setCurrentAccountIndex(_accounts.indexOf(account));
     Navigator.of(context).pushNamedAndRemoveUntil(Home.routeName, (_) => false,
         arguments: HomeArguments(account.account));
   }
@@ -111,7 +111,7 @@ class _AccountPickerDialogState extends State<AccountPickerDialog> {
     try {
       _removeAccount(account);
       setState(() {
-        _accounts = Pref.inst().getAccounts2()!;
+        _accounts = Pref().getAccounts2()!;
       });
       SnackBarManager().showSnackBar(SnackBar(
         content: Text(
@@ -135,9 +135,9 @@ class _AccountPickerDialogState extends State<AccountPickerDialog> {
 
   void _removeAccount(PrefAccount account) {
     _log.info("[_removeAccount] Remove account: ${account.account}");
-    final currentAccounts = Pref.inst().getAccounts2()!;
+    final currentAccounts = Pref().getAccounts2()!;
     final currentAccount =
-        currentAccounts[Pref.inst().getCurrentAccountIndex()!];
+        currentAccounts[Pref().getCurrentAccountIndex()!];
     final newAccounts = currentAccounts
         .where((element) => element.account != account.account)
         .toList();
@@ -145,7 +145,7 @@ class _AccountPickerDialogState extends State<AccountPickerDialog> {
     if (newAccountIndex == -1) {
       throw StateError("Active account not found in resulting account list");
     }
-    Pref.inst()
+    Pref()
       ..setAccounts2(newAccounts)
       ..setCurrentAccountIndex(newAccountIndex);
   }
diff --git a/lib/widget/album_browser.dart b/lib/widget/album_browser.dart
index 3cf80faf..d13a9a0e 100644
--- a/lib/widget/album_browser.dart
+++ b/lib/widget/album_browser.dart
@@ -241,7 +241,7 @@ class _AlbumBrowserState extends State<AlbumBrowser>
         _album!,
         actions: [
           if (_album!.albumFile!.isOwned(widget.account.username) &&
-              Pref.inst().isLabEnableSharedAlbumOr(false))
+              Pref().isLabEnableSharedAlbumOr(false))
             IconButton(
               onPressed: () => _onSharePressed(context),
               icon: const Icon(Icons.share),
@@ -250,7 +250,7 @@ class _AlbumBrowserState extends State<AlbumBrowser>
         ],
         menuItemBuilder: (_) => [
           if (_album!.albumFile!.isOwned(widget.account.username) &&
-              Pref.inst().isLabEnableSharedAlbumOr(false))
+              Pref().isLabEnableSharedAlbumOr(false))
             PopupMenuItem(
               value: _menuValueFixShares,
               child: Text(L10n.global().fixSharesTooltip),
@@ -642,7 +642,7 @@ class _AlbumBrowserState extends State<AlbumBrowser>
             height: k.photoThumbSize,
           );
           if ((_editAlbum ?? _album)?.sortProvider is AlbumTimeSortProvider &&
-              Pref.inst().isAlbumBrowserShowDateOr()) {
+              Pref().isAlbumBrowserShowDateOr()) {
             final date = dateHelper.onFile(item.file);
             if (date != null) {
               yield _DateListItem(date: date);
diff --git a/lib/widget/album_browser_mixin.dart b/lib/widget/album_browser_mixin.dart
index 258e0b29..f666c39a 100644
--- a/lib/widget/album_browser_mixin.dart
+++ b/lib/widget/album_browser_mixin.dart
@@ -26,7 +26,7 @@ mixin AlbumBrowserMixin<T extends StatefulWidget>
   @override
   initState() {
     super.initState();
-    _thumbZoomLevel = Pref.inst().getAlbumBrowserZoomLevelOr(0);
+    _thumbZoomLevel = Pref().getAlbumBrowserZoomLevelOr(0);
   }
 
   @protected
@@ -72,7 +72,7 @@ mixin AlbumBrowserMixin<T extends StatefulWidget>
             setState(() {
               _thumbZoomLevel = value.round();
             });
-            Pref.inst().setAlbumBrowserZoomLevel(_thumbZoomLevel);
+            Pref().setAlbumBrowserZoomLevel(_thumbZoomLevel);
           },
         ),
         if (album.albumFile?.path.startsWith(
diff --git a/lib/widget/archive_browser.dart b/lib/widget/archive_browser.dart
index 51145f1d..d917aa8a 100644
--- a/lib/widget/archive_browser.dart
+++ b/lib/widget/archive_browser.dart
@@ -62,7 +62,7 @@ class _ArchiveBrowserState extends State<ArchiveBrowser>
   initState() {
     super.initState();
     _initBloc();
-    _thumbZoomLevel = Pref.inst().getAlbumBrowserZoomLevelOr(0);
+    _thumbZoomLevel = Pref().getAlbumBrowserZoomLevelOr(0);
   }
 
   @override
@@ -187,7 +187,7 @@ class _ArchiveBrowserState extends State<ArchiveBrowser>
             setState(() {
               _thumbZoomLevel = value.round();
             });
-            Pref.inst().setAlbumBrowserZoomLevel(_thumbZoomLevel);
+            Pref().setAlbumBrowserZoomLevel(_thumbZoomLevel);
           },
         ),
       ],
diff --git a/lib/widget/dynamic_album_browser.dart b/lib/widget/dynamic_album_browser.dart
index 638c731f..57dc8747 100644
--- a/lib/widget/dynamic_album_browser.dart
+++ b/lib/widget/dynamic_album_browser.dart
@@ -549,7 +549,7 @@ class _DynamicAlbumBrowserState extends State<DynamicAlbumBrowser>
             height: k.photoThumbSize,
           );
           if ((_editAlbum ?? _album)?.sortProvider is AlbumTimeSortProvider &&
-              Pref.inst().isAlbumBrowserShowDateOr()) {
+              Pref().isAlbumBrowserShowDateOr()) {
             final date = dateHelper.onFile(item.file);
             if (date != null) {
               yield _DateListItem(date: date);
diff --git a/lib/widget/home.dart b/lib/widget/home.dart
index 0a1721cc..5e237a77 100644
--- a/lib/widget/home.dart
+++ b/lib/widget/home.dart
@@ -47,10 +47,10 @@ class _HomeState extends State<Home> {
   @override
   initState() {
     super.initState();
-    if (Pref.inst().isLabEnableSharedAlbumOr(false)) {
+    if (Pref().isLabEnableSharedAlbumOr(false)) {
       _importPotentialSharedAlbum().then((value) {
         if (value.isNotEmpty) {
-          Pref.inst().setNewSharedAlbum(true);
+          Pref().setNewSharedAlbum(true);
         }
       });
     }
@@ -131,7 +131,7 @@ class _HomeState extends State<Home> {
     final albumRepo = AlbumRepo(AlbumRemoteDataSource());
     try {
       return await ImportPotentialSharedAlbum(fileRepo, albumRepo)(
-          widget.account, Pref.inst().getAccountSettings(widget.account));
+          widget.account, Pref().getAccountSettings(widget.account));
     } catch (e, stacktrace) {
       _log.shout(
           "[_importPotentialSharedAlbum] Failed while ImportPotentialSharedAlbum",
diff --git a/lib/widget/home_albums.dart b/lib/widget/home_albums.dart
index ebc16ab4..dd8f74d6 100644
--- a/lib/widget/home_albums.dart
+++ b/lib/widget/home_albums.dart
@@ -241,7 +241,7 @@ class _HomeAlbumsState extends State<HomeAlbums>
     return _ButtonListItem(
       icon: Icons.share_outlined,
       label: L10n.global().collectionSharingLabel,
-      isShowIndicator: Pref.inst().hasNewSharedAlbumOr(false),
+      isShowIndicator: Pref().hasNewSharedAlbumOr(false),
       onTap: () {
         if (!isSelectionMode) {
           Navigator.of(context).pushNamed(SharingBrowser.routeName,
@@ -362,7 +362,7 @@ class _HomeAlbumsState extends State<HomeAlbums>
   }
 
   void _onSortSelected(_Sort sort) async {
-    await Pref.inst().setHomeAlbumsSort(sort.index);
+    await Pref().setHomeAlbumsSort(sort.index);
     setState(() {
       _transformItems(_bloc.state.items);
     });
@@ -443,7 +443,7 @@ class _HomeAlbumsState extends State<HomeAlbums>
       }
     }).map((e) => e.item2);
     itemStreamListItems = [
-      if (Pref.inst()
+      if (Pref()
               .getAccountSettings(widget.account)
               .isEnableFaceRecognitionApp ==
           true)
@@ -616,7 +616,7 @@ enum _Sort {
 
 _Sort _getSortFromPref() {
   try {
-    return _Sort.values[Pref.inst().getHomeAlbumsSort()!];
+    return _Sort.values[Pref().getHomeAlbumsSort()!];
   } catch (_) {
     // default
     return _Sort.dateDescending;
diff --git a/lib/widget/home_app_bar.dart b/lib/widget/home_app_bar.dart
index 6d8fdc13..342a8430 100644
--- a/lib/widget/home_app_bar.dart
+++ b/lib/widget/home_app_bar.dart
@@ -79,7 +79,7 @@ class HomeSliverAppBar extends StatelessWidget {
       automaticallyImplyLeading: false,
       actions: (actions ?? []) +
           [
-            if (!Pref.inst().isFollowSystemThemeOr(false))
+            if (!Pref().isFollowSystemThemeOr(false))
               Switch(
                 value: Theme.of(context).brightness == Brightness.dark,
                 onChanged: _onDarkModeChanged,
@@ -125,7 +125,7 @@ class HomeSliverAppBar extends StatelessWidget {
   }
 
   void _onDarkModeChanged(bool value) {
-    Pref.inst().setDarkTheme(value).then((_) {
+    Pref().setDarkTheme(value).then((_) {
       KiwiContainer().resolve<EventBus>().fire(ThemeChangedEvent());
     });
   }
diff --git a/lib/widget/home_photos.dart b/lib/widget/home_photos.dart
index e46ae9bc..9d0a8cef 100644
--- a/lib/widget/home_photos.dart
+++ b/lib/widget/home_photos.dart
@@ -69,7 +69,7 @@ class _HomePhotosState extends State<HomePhotos>
   @override
   initState() {
     super.initState();
-    _thumbZoomLevel = Pref.inst().getHomePhotosZoomLevelOr(0);
+    _thumbZoomLevel = Pref().getHomePhotosZoomLevelOr(0);
     _initBloc();
     _metadataTaskStateChangedListener.begin();
     _prefUpdatedListener.begin();
@@ -241,7 +241,7 @@ class _HomePhotosState extends State<HomePhotos>
               setState(() {
                 _setThumbZoomLevel(value.round());
               });
-              Pref.inst().setHomePhotosZoomLevel(_thumbZoomLevel);
+              Pref().setHomePhotosZoomLevel(_thumbZoomLevel);
             },
           ),
         ],
@@ -546,7 +546,7 @@ class _HomePhotosState extends State<HomePhotos>
     bool ignoreFired = false,
   }) {
     if (_bloc.state is ScanDirBlocSuccess &&
-        Pref.inst().isEnableExifOr() &&
+        Pref().isEnableExifOr() &&
         (!_hasFiredMetadataTask.value || ignoreFired)) {
       MetadataTaskManager().addTask(MetadataTask(widget.account));
       _metadataTaskProcessTotalCount = _backingFiles
diff --git a/lib/widget/my_app.dart b/lib/widget/my_app.dart
index 03a60e1e..23cd8238 100644
--- a/lib/widget/my_app.dart
+++ b/lib/widget/my_app.dart
@@ -61,11 +61,11 @@ class _MyAppState extends State<MyApp> implements SnackBarHandler {
   @override
   build(BuildContext context) {
     final ThemeMode themeMode;
-    if (Pref.inst().isFollowSystemThemeOr(false)) {
+    if (Pref().isFollowSystemThemeOr(false)) {
       themeMode = ThemeMode.system;
     } else {
       themeMode =
-          Pref.inst().isDarkThemeOr(false) ? ThemeMode.dark : ThemeMode.light;
+          Pref().isDarkThemeOr(false) ? ThemeMode.dark : ThemeMode.light;
     }
     return MaterialApp(
       onGenerateTitle: (context) => AppLocalizations.of(context)!.appTitle,
diff --git a/lib/widget/person_browser.dart b/lib/widget/person_browser.dart
index 9e67869b..1af7d713 100644
--- a/lib/widget/person_browser.dart
+++ b/lib/widget/person_browser.dart
@@ -84,7 +84,7 @@ class _PersonBrowserState extends State<PersonBrowser>
   initState() {
     super.initState();
     _initBloc();
-    _thumbZoomLevel = Pref.inst().getAlbumBrowserZoomLevelOr(0);
+    _thumbZoomLevel = Pref().getAlbumBrowserZoomLevelOr(0);
 
     _filePropertyUpdatedListener.begin();
   }
@@ -206,7 +206,7 @@ class _PersonBrowserState extends State<PersonBrowser>
             setState(() {
               _thumbZoomLevel = value.round();
             });
-            Pref.inst().setAlbumBrowserZoomLevel(_thumbZoomLevel);
+            Pref().setAlbumBrowserZoomLevel(_thumbZoomLevel);
           },
         ),
       ],
diff --git a/lib/widget/settings.dart b/lib/widget/settings.dart
index de078e24..22bea9bc 100644
--- a/lib/widget/settings.dart
+++ b/lib/widget/settings.dart
@@ -57,7 +57,7 @@ class _SettingsState extends State<Settings> {
   @override
   initState() {
     super.initState();
-    _isEnableExif = Pref.inst().isEnableExifOr();
+    _isEnableExif = Pref().isEnableExifOr();
   }
 
   @override
@@ -220,7 +220,7 @@ class _SettingsState extends State<Settings> {
 
   void _onLanguageTap(BuildContext context) {
     final selected =
-        Pref.inst().getLanguageOr(language_util.supportedLanguages[0]!.langId);
+        Pref().getLanguageOr(language_util.supportedLanguages[0]!.langId);
     showDialog(
       context: context,
       builder: (context) => FancyOptionPicker(
@@ -240,7 +240,7 @@ class _SettingsState extends State<Settings> {
       ),
     ).then((value) {
       if (value != null) {
-        Pref.inst().setLanguage(value).then((_) {
+        Pref().setLanguage(value).then((_) {
           KiwiContainer().resolve<EventBus>().fire(LanguageChangedEvent());
         });
       }
@@ -345,7 +345,7 @@ class _SettingsState extends State<Settings> {
     setState(() {
       _isEnableExif = value;
     });
-    if (!await Pref.inst().setEnableExif(value)) {
+    if (!await Pref().setEnableExif(value)) {
       _log.severe("[_setExifSupport] Failed writing pref");
       SnackBarManager().showSnackBar(SnackBar(
         content: Text(L10n.global().writePreferenceFailureNotification),
@@ -406,7 +406,7 @@ class _AccountSettingsState extends State<AccountSettingsWidget> {
     super.initState();
     _account = widget.account;
 
-    final settings = Pref.inst().getAccountSettings(_account);
+    final settings = Pref().getAccountSettings(_account);
     _isEnableFaceRecognitionApp = settings.isEnableFaceRecognitionApp;
     _shareFolder = settings.shareFolder;
   }
@@ -489,7 +489,7 @@ class _AccountSettingsState extends State<AccountSettingsWidget> {
         _log.fine("[_onIncludedFoldersPressed] No changes");
         return;
       }
-      final accounts = Pref.inst().getAccounts2()!;
+      final accounts = Pref().getAccounts2()!;
       if (accounts.any((element) => element.account == result)) {
         // conflict with another account. This normally won't happen because
         // the app passwords are unique to each entry, but just in case
@@ -515,7 +515,7 @@ class _AccountSettingsState extends State<AccountSettingsWidget> {
         account: result,
       );
       accounts[index] = newAccount;
-      if (!await Pref.inst().setAccounts2(accounts)) {
+      if (!await Pref().setAccounts2(accounts)) {
         SnackBarManager().showSnackBar(SnackBar(
           content: Text(L10n.global().writePreferenceFailureNotification),
           duration: k.snackBarDurationNormal,
@@ -605,7 +605,7 @@ class _AccountSettingsState extends State<AccountSettingsWidget> {
     String? shareFolder,
   }) {
     try {
-      final accounts = Pref.inst().getAccounts2()!;
+      final accounts = Pref().getAccounts2()!;
       final index = _findAccount(account, accounts);
       accounts[index] = accounts[index].copyWith(
         settings: accounts[index].settings.copyWith(
@@ -613,7 +613,7 @@ class _AccountSettingsState extends State<AccountSettingsWidget> {
               shareFolder: shareFolder,
             ),
       );
-      return Pref.inst().setAccounts2(accounts);
+      return Pref().setAccounts2(accounts);
     } catch (e, stackTrace) {
       _log.severe(
           "[_modifyAccountSettings] Failed while setting account settings",
@@ -625,7 +625,7 @@ class _AccountSettingsState extends State<AccountSettingsWidget> {
 
   /// Return the index of [account] in [Pref.getAccounts2]
   static int _findAccount(Account account, [List<PrefAccount>? accounts]) {
-    final from = accounts ?? Pref.inst().getAccounts2Or([]);
+    final from = accounts ?? Pref().getAccounts2Or([]);
     return from.indexWhere((element) => element.account == account);
   }
 
@@ -711,8 +711,8 @@ class _ViewerSettingsState extends State<_ViewerSettings> {
   @override
   initState() {
     super.initState();
-    _screenBrightness = Pref.inst().getViewerScreenBrightnessOr(-1);
-    _isForceRotation = Pref.inst().isViewerForceRotationOr(false);
+    _screenBrightness = Pref().getViewerScreenBrightnessOr(-1);
+    _isForceRotation = Pref().isViewerForceRotationOr(false);
   }
 
   @override
@@ -833,7 +833,7 @@ class _ViewerSettingsState extends State<_ViewerSettings> {
     setState(() {
       _screenBrightness = value;
     });
-    if (!await Pref.inst().setViewerScreenBrightness(value)) {
+    if (!await Pref().setViewerScreenBrightness(value)) {
       _log.severe("[_setScreenBrightness] Failed writing pref");
       SnackBarManager().showSnackBar(SnackBar(
         content: Text(L10n.global().writePreferenceFailureNotification),
@@ -850,7 +850,7 @@ class _ViewerSettingsState extends State<_ViewerSettings> {
     setState(() {
       _isForceRotation = value;
     });
-    if (!await Pref.inst().setViewerForceRotation(value)) {
+    if (!await Pref().setViewerForceRotation(value)) {
       _log.severe("[_setForceRotation] Failed writing pref");
       SnackBarManager().showSnackBar(SnackBar(
         content: Text(L10n.global().writePreferenceFailureNotification),
@@ -877,7 +877,7 @@ class _AlbumSettingsState extends State<_AlbumSettings> {
   @override
   initState() {
     super.initState();
-    _isBrowserShowDate = Pref.inst().isAlbumBrowserShowDateOr();
+    _isBrowserShowDate = Pref().isAlbumBrowserShowDateOr();
   }
 
   @override
@@ -920,7 +920,7 @@ class _AlbumSettingsState extends State<_AlbumSettings> {
     setState(() {
       _isBrowserShowDate = value;
     });
-    if (!await Pref.inst().setAlbumBrowserShowDate(value)) {
+    if (!await Pref().setAlbumBrowserShowDate(value)) {
       _log.severe("[_onBrowserShowDateChanged] Failed writing pref");
       SnackBarManager().showSnackBar(SnackBar(
         content: Text(L10n.global().writePreferenceFailureNotification),
@@ -946,8 +946,8 @@ class _ThemeSettingsState extends State<_ThemeSettings> {
   @override
   initState() {
     super.initState();
-    _isFollowSystemTheme = Pref.inst().isFollowSystemThemeOr(false);
-    _isUseBlackInDarkTheme = Pref.inst().isUseBlackInDarkThemeOr(false);
+    _isFollowSystemTheme = Pref().isFollowSystemThemeOr(false);
+    _isUseBlackInDarkTheme = Pref().isUseBlackInDarkThemeOr(false);
   }
 
   @override
@@ -999,7 +999,7 @@ class _ThemeSettingsState extends State<_ThemeSettings> {
     setState(() {
       _isFollowSystemTheme = value;
     });
-    if (await Pref.inst().setFollowSystemTheme(value)) {
+    if (await Pref().setFollowSystemTheme(value)) {
       KiwiContainer().resolve<EventBus>().fire(ThemeChangedEvent());
     } else {
       _log.severe("[_onFollowSystemThemeChanged] Failed writing pref");
@@ -1018,7 +1018,7 @@ class _ThemeSettingsState extends State<_ThemeSettings> {
     setState(() {
       _isUseBlackInDarkTheme = value;
     });
-    if (await Pref.inst().setUseBlackInDarkTheme(value)) {
+    if (await Pref().setUseBlackInDarkTheme(value)) {
       if (Theme.of(context).brightness == Brightness.dark) {
         KiwiContainer().resolve<EventBus>().fire(ThemeChangedEvent());
       }
@@ -1049,7 +1049,7 @@ class _ExperimentalSettingsState extends State<_ExperimentalSettings> {
   @override
   initState() {
     super.initState();
-    _isEnableSharedAlbum = Pref.inst().isLabEnableSharedAlbumOr(false);
+    _isEnableSharedAlbum = Pref().isLabEnableSharedAlbumOr(false);
   }
 
   @override
@@ -1092,7 +1092,7 @@ class _ExperimentalSettingsState extends State<_ExperimentalSettings> {
     setState(() {
       _isEnableSharedAlbum = value;
     });
-    if (!await Pref.inst().setLabEnableSharedAlbum(value)) {
+    if (!await Pref().setLabEnableSharedAlbum(value)) {
       _log.severe("[_onEnableSharedAlbumChanged] Failed writing pref");
       SnackBarManager().showSnackBar(SnackBar(
         content: Text(L10n.global().writePreferenceFailureNotification),
diff --git a/lib/widget/setup.dart b/lib/widget/setup.dart
index d0d431e2..2f071996 100644
--- a/lib/widget/setup.dart
+++ b/lib/widget/setup.dart
@@ -8,8 +8,7 @@ import 'package:nc_photos/widget/home.dart';
 import 'package:nc_photos/widget/sign_in.dart';
 import 'package:page_view_indicators/circle_page_indicator.dart';
 
-bool isNeedSetup() =>
-    Pref.inst().getSetupProgressOr() & _PageId.all != _PageId.all;
+bool isNeedSetup() => Pref().getSetupProgressOr() & _PageId.all != _PageId.all;
 
 class Setup extends StatefulWidget {
   static const routeName = "/setup";
@@ -102,9 +101,9 @@ class _SetupState extends State<Setup> {
   }
 
   void _onDonePressed() {
-    Pref.inst().setSetupProgress(_PageId.all);
+    Pref().setSetupProgress(_PageId.all);
 
-    final account = Pref.inst().getCurrentAccount();
+    final account = Pref().getCurrentAccount();
     if (account == null) {
       Navigator.pushReplacementNamed(context, SignIn.routeName);
     } else {
@@ -114,12 +113,12 @@ class _SetupState extends State<Setup> {
   }
 
   void _onNextPressed(int pageId) {
-    Pref.inst().setSetupProgress(Pref.inst().getSetupProgressOr() | pageId);
+    Pref().setSetupProgress(Pref().getSetupProgressOr() | pageId);
     _pageController.nextPage(
         duration: k.animationDurationNormal, curve: Curves.easeInOut);
   }
 
-  final _initialProgress = Pref.inst().getSetupProgressOr();
+  final _initialProgress = Pref().getSetupProgressOr();
   final _pageController = PageController();
   final _currentPageNotifier = ValueNotifier<int>(0);
 }
@@ -178,7 +177,7 @@ class _ExifState extends State<_Exif> {
   dispose() {
     super.dispose();
     // persist user's choice
-    Pref.inst().setEnableExif(_isEnableExif);
+    Pref().setEnableExif(_isEnableExif);
   }
 
   void _onValueChanged(bool value) {
@@ -187,7 +186,7 @@ class _ExifState extends State<_Exif> {
     });
   }
 
-  bool _isEnableExif = Pref.inst().isEnableExifOr();
+  bool _isEnableExif = Pref().isEnableExifOr();
 }
 
 class _HiddenPrefDirNotice extends StatefulWidget implements _Page {
diff --git a/lib/widget/sharing_browser.dart b/lib/widget/sharing_browser.dart
index 1bf243d2..8cf9f7c1 100644
--- a/lib/widget/sharing_browser.dart
+++ b/lib/widget/sharing_browser.dart
@@ -61,11 +61,11 @@ class _SharingBrowserState extends State<SharingBrowser> {
   @override
   initState() {
     super.initState();
-    if (Pref.inst().isLabEnableSharedAlbumOr(false)) {
+    if (Pref().isLabEnableSharedAlbumOr(false)) {
       _importPotentialSharedAlbum().whenComplete(() {
         _initBloc();
       });
-      Pref.inst().setNewSharedAlbum(false);
+      Pref().setNewSharedAlbum(false);
     } else {
       _initBloc();
     }
@@ -321,7 +321,7 @@ class _SharingBrowserState extends State<SharingBrowser> {
     final albumRepo = AlbumRepo(AlbumRemoteDataSource());
     try {
       return await ImportPotentialSharedAlbum(fileRepo, albumRepo)(
-          widget.account, Pref.inst().getAccountSettings(widget.account));
+          widget.account, Pref().getAccountSettings(widget.account));
     } catch (e, stackTrace) {
       _log.shout(
           "[_importPotentialSharedAlbum] Failed while ImportPotentialSharedAlbum",
diff --git a/lib/widget/sign_in.dart b/lib/widget/sign_in.dart
index 4b38ca78..cfeea407 100644
--- a/lib/widget/sign_in.dart
+++ b/lib/widget/sign_in.dart
@@ -228,11 +228,11 @@ class _SignInState extends State<SignIn> {
         // we've got a good account
         final pa = PrefAccount(result);
         // only signing in with app password would trigger distinct
-        final accounts = (Pref.inst().getAccounts2Or([])..add(pa)).distinctIf(
+        final accounts = (Pref().getAccounts2Or([])..add(pa)).distinctIf(
           (a, b) => a.account == b.account,
           (a) => a.account.hashCode,
         );
-        Pref.inst()
+        Pref()
           ..setAccounts2(accounts)
           ..setCurrentAccountIndex(
               accounts.indexWhere((element) => element.account == result));
diff --git a/lib/widget/splash.dart b/lib/widget/splash.dart
index 55957843..9b963129 100644
--- a/lib/widget/splash.dart
+++ b/lib/widget/splash.dart
@@ -74,7 +74,7 @@ class _SplashState extends State<Splash> {
 
   void _initTimedExit() {
     Future.delayed(const Duration(seconds: 1)).then((_) {
-      final account = Pref.inst().getCurrentAccount();
+      final account = Pref().getCurrentAccount();
       if (isNeedSetup()) {
         Navigator.pushReplacementNamed(context, Setup.routeName);
       } else if (account == null) {
@@ -87,13 +87,13 @@ class _SplashState extends State<Splash> {
   }
 
   bool _shouldUpgrade() {
-    final lastVersion = Pref.inst().getLastVersionOr(k.version);
+    final lastVersion = Pref().getLastVersionOr(k.version);
     return lastVersion < k.version;
   }
 
   void _handleUpgrade() async {
     try {
-      final lastVersion = Pref.inst().getLastVersionOr(k.version);
+      final lastVersion = Pref().getLastVersionOr(k.version);
       await _upgrade(lastVersion);
 
       final change = _gatherChangelog(lastVersion);
@@ -118,7 +118,7 @@ class _SplashState extends State<Splash> {
       }
     } finally {
       _initTimedExit();
-      Pref.inst().setLastVersion(k.version);
+      Pref().setLastVersion(k.version);
     }
   }
 
diff --git a/lib/widget/trashbin_browser.dart b/lib/widget/trashbin_browser.dart
index deb886b0..c7800f80 100644
--- a/lib/widget/trashbin_browser.dart
+++ b/lib/widget/trashbin_browser.dart
@@ -63,7 +63,7 @@ class _TrashbinBrowserState extends State<TrashbinBrowser>
   initState() {
     super.initState();
     _initBloc();
-    _thumbZoomLevel = Pref.inst().getAlbumBrowserZoomLevelOr(0);
+    _thumbZoomLevel = Pref().getAlbumBrowserZoomLevelOr(0);
   }
 
   @override
@@ -209,7 +209,7 @@ class _TrashbinBrowserState extends State<TrashbinBrowser>
             setState(() {
               _thumbZoomLevel = value.round();
             });
-            Pref.inst().setAlbumBrowserZoomLevel(_thumbZoomLevel);
+            Pref().setAlbumBrowserZoomLevel(_thumbZoomLevel);
           },
         ),
         PopupMenuButton<_AppBarMenuOption>(
diff --git a/lib/widget/viewer.dart b/lib/widget/viewer.dart
index 7a1ee29a..a5f2ca5d 100644
--- a/lib/widget/viewer.dart
+++ b/lib/widget/viewer.dart
@@ -481,15 +481,15 @@ class _ViewerState extends State<Viewer>
     final result = await showDialog<SlideshowConfig>(
       context: context,
       builder: (_) => SlideshowDialog(
-        duration: Duration(seconds: Pref.inst().getSlideshowDurationOr(5)),
-        isShuffle: Pref.inst().isSlideshowShuffleOr(false),
-        isRepeat: Pref.inst().isSlideshowRepeatOr(false),
+        duration: Duration(seconds: Pref().getSlideshowDurationOr(5)),
+        isShuffle: Pref().isSlideshowShuffleOr(false),
+        isRepeat: Pref().isSlideshowRepeatOr(false),
       ),
     );
     if (result == null) {
       return;
     }
-    Pref.inst()
+    Pref()
       ..setSlideshowDuration(result.duration.inSeconds)
       ..setSlideshowShuffle(result.isShuffle)
       ..setSlideshowRepeat(result.isRepeat);
diff --git a/lib/widget/viewer_mixin.dart b/lib/widget/viewer_mixin.dart
index 8efcd0fb..5f238fa8 100644
--- a/lib/widget/viewer_mixin.dart
+++ b/lib/widget/viewer_mixin.dart
@@ -17,7 +17,7 @@ mixin ViewerControllersMixin<T extends StatefulWidget>
       ...super.initDisposables(),
       if (platform_k.isMobile) _ViewerBrightnessController(),
       _ViewerSystemUiResetter(),
-      if (platform_k.isMobile && Pref.inst().isViewerForceRotationOr(false))
+      if (platform_k.isMobile && Pref().isViewerForceRotationOr(false))
         _ViewerOrientationController(
           onChanged: _onOrientationChanged,
         ),
@@ -57,7 +57,7 @@ mixin ViewerControllersMixin<T extends StatefulWidget>
 class _ViewerBrightnessController implements Disposable {
   @override
   init(State state) {
-    final brightness = Pref.inst().getViewerScreenBrightness();
+    final brightness = Pref().getViewerScreenBrightness();
     if (brightness != null && brightness >= 0) {
       ScreenBrightness.setScreenBrightness(brightness / 100.0);
     }