Microsoft Surface Duo
Selecting ring tone
You can select the ring tone you want to hear when you get a call.
Slide two fingers downwards starting from the top of the screen.
Press the settings icon.
Press Sound.
Press Phone ringtone.
Press Add ringtone.
Press the required ring tone.
Press the required ring tones to hear them.
Once you've found a ring tone you like, press OK.
Slide your finger upwards starting from the bottom of the screen to return to the home screen.