Thank you for sharing your query. We would like to inform you that kindly follow below mention steps to lock apps in device:
1. Launch the S Secure app.
2. Under LOCK AND MASK APPS, tap TURN ON and tap the switch to activate it.
3. Select an app lock type and set your app unlock code.
4. Now, you can lock apps or hide them from the Home screen and Apps screen.
5. Tap Locked apps → ADD, select an app to lock and then tap DONE. The app will be locked after the screen turns off. You must enter the unlock code to launch the locked apps. Once an app is unlocked, it will remain unlocked until the screen turns off.