Xiaomi
Turn On App Lock auf Xiaomi
MIUI includes a built-in App lock feature that requires a separate password, pattern, or fingerprint before an app opens, even if the phone itself is already unlocked. This matters because your screen lock only protects the home screen. Once someone has that PIN, they can open every app unless individual apps are locked separately.
The setting lives under app management, not under the general lock screen options, which is why many users never find it. To turn it on, go to Tap on Settings ➔ Tap on Apps ➔ Tap on App lock ➔ Tap on Turn on and set a Pattern. MIUI then asks whether to link the lock to your Mi account: choose Not now to skip this, or Sign in & add to enable account recovery for the lock.
On the next screen, Select or deselect the suggested Apps and tap Use App lock to confirm which apps require the extra step. You can add fingerprint unlocking and notification-content hiding from the same App lock menu afterward. If you only want to hide notification previews without locking apps, check the notification privacy settings instead, since App lock adds an extra unlock step every time you open a protected app.