Of course the answer is more training ultimately. But in the meantime a bit that actually works is a miracle device, so yes, find a bit he likes AND that gives you control!
With that issue I’ve had lots of luck with Mylers (hunter gags) where you can add a curb chain for a bit “more”. And gag bits in general. Find a mouthpiece you like and then try a gag version of it. I showed my TB in the big jumpers in a slow twist gag for years.
Another one that was an absolute miracle bit for one of my mares is a myler 3-ring combination bit with a nose rope and curb strap. My mare loves to curl behind the bit with too much, but the combination effect seems to keep her happy. But she’s super peculiar, and that bit has not been the same miracle on any of my other horses.