Re: Disable app sounds
I think you're talking about Touch Sounds, which are completely different from notification tones, and cannot be modified (only turned on or off). On most phones, that setting is in Settings>Sound. Is that where you found your setting?
Well, I did not mention notifications until I said "I am not talking about notifications".
I don't want to modify those sounds.
I found a setting within facebook that switched them off, for facebook. (There was only a setting to switch off video sound when playing, which I also switched off and I cannot imagine why anybody would think that would be a useful thing to have on as a default.)
In my phone's settings there is a "Sound & vibration" and this is where "Media" volume is off and "Ringtone", "Notifications", and "Alarms" are on. But for some reason touch sounds do not count as "Media" but apparently as one of the other three, I forgot which one.
There is also a category "Haptics and tones" which is turned off but also doesn't affect touch sounds.