Don’t use your heel and sit back once you land
When you land. Sit back and sit deep. Keep contact but don’t pull at his face. He will only fight it. And maybe try trotting the jump so he can’t build faster after
Make sure you’re not catching him in the mouth after the jump and giving a proper release over the jump. They usually bolt after the jump due to rider error
Set poles before and after the jump to get him focaused on him striding in and out of the pole
My trainer makes a square with poles around 5 strides (or less) after the jump for us to halt the horse in (:
I had a horse like this as well. I did a lot of grid work. Also set up poles as bounces and one strides before are after a fence. Don't interfere with your horse by pulling on his mouth etc. Stay relaxed and if he wants to blow every fence put let him be patient and he will learn. This worked wonderfully with my ,are and she's now doing 120. ! Best of luck :)
Sit back and hold him back a bit and/or half halt. When training stop him right after the jump or bring him back to a walk or trot straight away before he starts to bolt.
I used to have a horse like this and my trainer has always said to approach the jump normally but stop right before it and wait a little bit. Then turn around and just trot or walk over it again and halt after. You can repeat this as many times as you want and when your comfortable you can canter in. When you do halt after and repeat that. It really just helps the horse understand everything alright and there is no need to bolt! Hope everything turns out the way you want, good luck!!
For that kind of horses we usually do half halt when we are approaching the fence. As many as needed but not pulling and bracing too long. And not longer than 1 stride. That will make your horse more attentive then after the fence stop him on a straight line million times if needed. Use your voice, your weight more than strong hands. The more you do it the more horse will understand. Be careful to stop straight after 2-3 stride, ıf you do it on the turn or if you use turn to control, that wont be solving your problem. At the beginning until your horse understands you can get stronger a little bit. But in time try to do it softer. It needs time and patience. Good luck