One of the biggest problems most parents of newly diagnosed children face is keeping the hearing aids on the child. Even some who have been wearing hearing aids for a while persist on taking them out.
Lets look at it from the child's point of view.
Suddenly these things are stuffed into their ears and fill their world with noise, lots of it. Their first response is, quite naturally, to get rid of these things. If he takes them out 1000 times in one day, you put them back in 1001. Don't show anger. Don't show frustration.