Personalise the navigation bar
All Lumia phones have 3 keys across the bottom: the back, start, and search key. You can change the 
way this navigation bar behaves.
Switch the vibration of the navigation keys on or off
On the start screen, swipe down from the top of the screen, tap ALL SETTINGS > touch, and change 
the setting for navigation bar.
Changing the vibration setting for incoming calls doesn’t affect the vibration of the navigation keys.