When you go over a fence make sure you don't lay on his neck, it would cause him to knock the rials in the front legs as he has got your weight on his front legs.
And keep your legs under your self!! That will make him go froward better!
How old is he? He may have a future in front of him!
Also if you lift your hands he will look up and won't jump so flat.
I am not putting you down, but if you take my advice you will do well with your horse!!
The picture below might help you, it is my daughter....