Change System navigation
You can choose how to move between apps and screens:
1. Go to Settings > System > Gestures.
2. Tap System navigation.
3. Choose an option:
•
Gesture navigation: Use drag and swipe gestures to return to your home screen, to switch apps, 
or to go back to the previous screen. Learn more about gestures. To adjust sensitivity of the back 
gesture, touch   and move the slider.
•
3-button navigation: Use the     and   buttons. Learn more.
Settings : System : Gestures 270