Android has its own screen lock, but it does not always meet expectations. Before using a different screen lock, you must deactivate the one that is installed by default.
To use a different screen lock you must first deactivate the Google screen lock. Otherwise, you will have to unlock the phone twice every time you want to use it.
Disabling Android’s screen lock is very easy. Go to Settings > Security and then choose None. Before doing that, you will have to enter you current code or pattern.
If you can’t disable the system lock, press Clear credentials in Settings > Security, as they may interfere. Also disable third-party apps in Device administrators.
Now you can use any other application to lock the screen and protect it from eavesdroppers. We recommend Screen Lock Guardian.