Call tone, text tone, and sound when music plays on phone not working.

My bf has a ZTE zmax phone and when people call, or text no sound plays, the volume is all the way up for notifications and calls. We've tried resetting his phone, turning it on and off and can't seem to find the problem.

Also when he gets on YouTube to play music the volume isn't working but if he connects to our Bluetooth speaker it will work.