Hello! I have a arab/quarter horse who is 7 years old. He is pretty green. My concern is that he is very unpredictable. When we go on trial rides he will always try to take any random corner he can. He will veer off into driveways/ lawns, any corner he feels like taking. I've tried to apply pressure with which ever leg he is turning in the direction of, even kicking him on that side. I hate to keep pulling on his mouth. He will also go left and right when we are going down a road, like he just cant go straight. I read somewhere that if your horses tail is sideway/crooked that it means your horses spine is not straight. My horses tail is always to the right. Could a crooked spine be a reason he doesn't like to go straight?

it sounds like a problem we had with one of our horses. in his case, he wanted to end the ride. is there a reason for your horse to dislike trail riding?

Sounds like you need to spend some arena time with your horse. Once you get him paying attention to you in the arena then you should take it back out to the trail.

Good luck and take it slow.