Set default notification sound
To change the sound used for notifications from all apps:
Do one of the following:
Set notification sound for a specific app
To use a distinctive sound for an app's notifications, instead of the default notification sound:
Tap the category for enabled notifications, then tap Advanced > Sound and select a unique ringtone, or set it to none.
If you can't hear a notification
To let an app's notifications be heard when Do Not Disturb is on: