Re: Volume Control...
Maybe seeing a visual of how what volumes are acceptable would help? They make apps that measure noise level (think back when you were in school did one of your teachers have the traffic light that moved to yellow or red if the room was getting too loud?).
I haven't tried it yet, but there is a free app for iphone called Too Noisy that looks cute and kid friendly. It could even be a game for the first few times you use if of How long can you go without getting to the RED or whatever.