1. From the home screen, drag down from the top of the screen with two fingers to reveal the quick settings menu.
   
2. Tap the Settings icon.
   
3. Scroll to 'PHONE', then tap Sound & notification.
   
4. Scroll to 'INCOMING CALLS', then tap Ringtone.
   
5. Tap the desired ringtone.
   
6. Tap APPLY.