Ah, if he’s hearing well with the hearing aids and the problem is just bluetooth, I wouldn’t change the fitting formula because that will also change the sound of the hearing aids - I think it might be better to change just the bluetooth programs!
-If the sound of people talking on a phone call is too loud, the audiologist can go into the ‘media speech + mic’ program (in the picture above) and turn that down
-If it’s spotify or youtube that’s too loud, the audiologist can go into the ‘media music + mic’ program and turn that down
-If it’s things like app notifications that are too loud (ie you get a notification from your weather app, and it’s way too loud) - I find it’s better to go into your phone settings, manually turn off sounds for all the various apps or change them to vibrate only, that way you still get the notification on the phone, and it will vibrate to let you know, but it won’t play the sound through the hearing aid
Hope this helps!