Tap on 'More' on the bottom menu

Tap 'Settings', then 'General Settings'

Scroll down and tap on 'Sound' under the Notifications section

Select to not receive sound or tap 'Ringtone' to choose a new Medtone or sound option

Tap on 'More' on the bottom menu

Tap on 'Settings'

Tap on 'Medtones' to choose a new sound. Device loaded sounds will be located at the bottom of the list