Question: how to change notification sound by app on iphone?
Answer: Tap Sounds & Haptics. Meira Gebel/Business Insider.
Change the notification sound under Sounds and Vibration Patterns. Meira Gebel/Business Insider.
Select a new notification sound. ... 
Select the app you want to enable notification sounds for. ... 
Tap to allow notifications. ... 
Notification sounds are now enabled.