Where can i change the sound of the app

You can't change the sounds. These are not Apple owned products. So you should contact the app developers of these products for help.

Update now. All my notification sounds are changed. These are not app set sounds. The app is set to I phone sound for notifications selection. These are iPhone set. There’s no menu in the new software to change the sounds back to the old sounds the ones I’m familiar with the ones I can hear the ones I like. The one menu that let you set sounds does not change anything. Some engineer thought it would be cute to change the sounds. Some people like the sounds the way they are set before the upgrade. Apple needs to quit changing customer settings with upgrades. Or at least post a question would you like to change notification sounds to some new stupid sound that you do not like looks like an android in my future.