Galaxy S6: How to pin applications to the screen?
You can pin an application to the screen of your device. This feature locks your device so the person using it has access to only the pinned application. Pinning an application also prevents other applications and features from causing interruptions, and it keeps you from accidentally exiting the application.
Turn on Pin Windows
Pin an application to the screen
With the Pin windows feature turned on, you can pin an application to your screen.
Note: Calling, messaging, and other functions may not be available while an application is pinned to the screen. Access to other applications will be prevented.