View this info to change the notification sound for incoming calls and/or messages.
From a Home screen, navigate: Apps icon > Settings > Sound & notification.
If Settings is unavailable, tap the Dropdown menu (located in the upper left) then select Alphabetical. If still unavailable, refer to Manage App Icons.
If you don't see dropdown notifications for an app, check that the Block switch is turned off in the app.
The Sound profile option (at top of the screen) must be set to Normal to modify ringtone/notification/alarm selections.