How to change the notification sounds in Lumia 950 & 950 XL? You can customize the sound per app. It’s not very obvious in the Settings, so I’ll show you how to do it. Go to Settings (Swipe down from top of the screen and tap All Settings) Tap System > Notifications & actions Tap ...
Source: WindowsPhonehub
Read Full post here How to change the notification sounds in Lumia 950 & 950 XL? or Visit WindowsPhonehub.