half halts and sitting into the saddle help for me. if he does something funky or something "rude" halt him then take a few steps back.
Sit tall and really deepen your seat and tighten your core
Just do a lot of practice! Don't release pressure until he responds and as soon as he does release all pressure and reward him and do this over and over.
Lots of half halting, make sure you're not hanging on his mouth, and use a pulley rein a few to,es just to show him you have that I your toll box and he can't get anywaywith much, hope this helps 😊
If he won't stop trotting ask him to canter and make him do some work, do a lot of circles, lead changes, just any work to make him realize that hes doing more work then he has to. Then work on your transitions, reward him when he does good transitions, once you get where you want try to stay there a little but then relax and praise him. Basically make him think hes doing more work then he has to and he'll realize that he wants to only do what you want not more.
Hope it helps.