"Screen Pinning” will cause the phone to stay on a single app and allow you to control its available functions.
Note： Incoming calls, alarms, and more will be affected after this function is enable.
Important Note：Navigation keys must be set to "virtual keys" (Settings->Convenience Aid->Navigation Keys->Virtual Keys).
Steps：Settings->Additional Settings->Device& Privacy->Screen Pinning.
Enter the multi-task -> Click on the top right corner -> Select Fixed.
Note：No APP can be installed after fixing Fire Manager.
How to quit it?
At the same time, press the back key and recent key to cancel this locked screen. When the fixed screen is cancelled, it will enter the lock screen state directly.
Have to leave the device or borrow it for friends, but you don't want them use other functions. You can enable this function to fix a specific application, which can effectively guarantee privacy.