This article describes how to change the device's alerts.
INSTRUCTIONS & INFO
To change your ringtone from Settings, tap Sounds and Notifications.
Tap Change your ringtone.
Tap Sound.
Tap the name of a sound to hear a sample.
Select a sound to use it as your ringtone. If you don't want a ringtone, tap None at the top.
To modify notification settings, from Settings, tap Sounds and Notifications.
Tap Manage Notifications.
Select an app from the list to customize whether notifications from that app appear in the top panel, display a banner at the top of the screen, and/or play a sound.