AmyMay
Situation normal
OP you have been given suggestions, stick summat stronger in his gob like a waterford that he can't lean on and that you can get his attention with. When my boy was young he liked to pi$$ off at rideouts and a dr bristol with a flash soon stopped that behaviour, he had a pretty sore gob that day and learned I'm not entertaining it.
It's also really important to learn to ride the horse more effectively as well as putting a stronger bit in it's mouth.