diff --git a/backend/open_webui/routers/configs.py b/backend/open_webui/routers/configs.py
index c286152abd..fd2ad14602 100644
--- a/backend/open_webui/routers/configs.py
+++ b/backend/open_webui/routers/configs.py
@@ -676,9 +676,19 @@ class InterfaceDefaultsForm(BaseModel):
     @field_validator("chatDirection")
     @classmethod
     def validate_chat_direction(cls, value):
-        if value is not None and value not in ("auto", "ltr", "rtl"):
-            raise ValueError("chatDirection must be 'auto', 'ltr', or 'rtl'")
-        return value
+        # The user-side store is typed 'LTR' | 'RTL' | 'auto' and the
+        # Interface settings toggle cycles uppercase values, so accept any
+        # casing and normalize to the shape the frontend expects. Rejecting
+        # the uppercase values outright (as the validator did before) made
+        # the modal fail with a 422 on every LTR/RTL save.
+        if value is None:
+            return value
+        normalized = value.lower()
+        if normalized == "auto":
+            return "auto"
+        if normalized in ("ltr", "rtl"):
+            return normalized.upper()
+        raise ValueError("chatDirection must be 'auto', 'LTR', or 'RTL'")
 
     @field_validator("textScale")
     @classmethod
diff --git a/src/lib/apis/configs/index.ts b/src/lib/apis/configs/index.ts
index 7cbdad0431..df16b033d2 100644
--- a/src/lib/apis/configs/index.ts
+++ b/src/lib/apis/configs/index.ts
@@ -664,7 +664,12 @@ export const getInterfaceDefaults = async (token: string) => {
 		})
 		.catch((err) => {
 			console.error(err);
-			error = err.detail;
+			// Fall back through detail / message / stringification so a
+			// network TypeError or non-JSON response still produces a truthy
+			// error — otherwise the function silently returned null and the
+			// caller couldn't tell a failed fetch from an empty-defaults
+			// response.
+			error = err?.detail ?? err?.message ?? (typeof err === 'string' ? err : 'Request failed');
 			return null;
 		});
 
@@ -692,7 +697,7 @@ export const setInterfaceDefaults = async (token: string, defaults: object) => {
 		})
 		.catch((err) => {
 			console.error(err);
-			error = err.detail;
+			error = err?.detail ?? err?.message ?? (typeof err === 'string' ? err : 'Request failed');
 			return null;
 		});
 
diff --git a/src/lib/apis/users/index.ts b/src/lib/apis/users/index.ts
index b599f0b7fc..23e8eca5df 100644
--- a/src/lib/apis/users/index.ts
+++ b/src/lib/apis/users/index.ts
@@ -567,7 +567,11 @@ export const resetAllUsersInterfaceSettings = async (token: string) => {
 		})
 		.catch((err) => {
 			console.error(err);
-			error = err.detail;
+			// Fall back through detail / message / stringification so a
+			// network TypeError or non-JSON response still produces a truthy
+			// error — otherwise the function silently returned null and the
+			// caller could mistake a failed reset for a silent success.
+			error = err?.detail ?? err?.message ?? (typeof err === 'string' ? err : 'Request failed');
 			return null;
 		});
 
diff --git a/src/lib/components/admin/Settings/Interface.svelte b/src/lib/components/admin/Settings/Interface.svelte
index 204415910c..8bec5c8606 100644
--- a/src/lib/components/admin/Settings/Interface.svelte
+++ b/src/lib/components/admin/Settings/Interface.svelte
@@ -114,6 +114,42 @@
 		}}
 	>
 		<div class="  overflow-y-scroll scrollbar-hidden h-full pr-1.5">
+			<div class="mb-3.5">
+				<div class=" mt-0.5 mb-2.5 text-base font-medium">
+					{$i18n.t('Interface Defaults')}
+				</div>
+
+				<hr class=" border-gray-100/30 dark:border-gray-850/30 my-2" />
+
+				<div class="text-xs text-gray-500 dark:text-gray-400 mb-2">
+					{$i18n.t(
+						"Configure default interface settings that apply to all users who haven't customized their own."
+					)}
+				</div>
+
+				<div class="flex flex-col sm:flex-row gap-2">
+					<button
+						type="button"
+						class="px-3 py-1.5 text-xs font-medium rounded-lg border border-gray-200 dark:border-gray-800 hover:bg-gray-100 dark:hover:bg-gray-850 transition"
+						on:click={() => {
+							showInterfaceDefaultsModal = true;
+						}}
+					>
+						{$i18n.t('Configure Defaults')}
+					</button>
+
+					<button
+						type="button"
+						class="px-3 py-1.5 text-xs font-medium rounded-lg border border-red-300 dark:border-red-900/50 text-red-600 dark:text-red-400 hover:bg-red-50 dark:hover:bg-red-950/30 transition"
+						on:click={() => {
+							showResetConfirmDialog = true;
+						}}
+					>
+						{$i18n.t('Reset All Users Interface Settings')}
+					</button>
+				</div>
+			</div>
+
 			<div class="mb-3.5">
 				<div class=" mt-0.5 mb-2.5 text-base font-medium">{$i18n.t('Tasks')}</div>
 
diff --git a/src/routes/+layout.svelte b/src/routes/+layout.svelte
index 480f01f2c4..165465eafa 100644
--- a/src/routes/+layout.svelte
+++ b/src/routes/+layout.svelte
@@ -929,14 +929,15 @@
 					})
 				]);
 
-				// Admin defaults are base, user settings override.
-				const effectiveSettings = deepMerge(adminDefaults ?? {}, userSettings?.ui ?? {});
-
-				if (userSettings) {
-					settings.set(effectiveSettings);
-				} else {
-					settings.set(JSON.parse(localStorage.getItem('settings') ?? '{}'));
-				}
+				// Admin defaults are the base layer; whatever the user has
+				// actually customized overrides them. For brand-new users
+				// getUserSettings() returns null — the whole point of admin
+				// defaults is that THOSE users get them, so always merge
+				// against adminDefaults instead of skipping straight to
+				// localStorage when userSettings is falsy.
+				const localStorageSettings = JSON.parse(localStorage.getItem('settings') ?? '{}');
+				const userUI = userSettings?.ui ?? localStorageSettings ?? {};
+				settings.set(deepMerge(adminDefaults ?? {}, userUI));
 				setTextScale($settings?.textScale ?? 1);
 
 				// Set up the token expiry check