I don't know how to make this horse get it when I am happy with something he does using the conventional methods of saying, "Goood boyyyyy!" doesn't work. Petting in the places on their body that they tell you to pat doesn't work. Food just encourages him to be more mouthy and he bites and looks for more treats,.... I pet him on the neck and say goood boyyy and he reaches over to bite me. That is what this horse is like. Lol
If you're saying "Goood Boooy" & haven't already established, through associating it with positive reinforcement, what you want it to mean to him, you may as well say "Blah blah BlaaaaH". Whatever cue, praise, whatever, you want the horse to understand, it needs to be taught with repetition of immediate consequences.
Petting is often something that fearful, untrusting horses perceive as punishment, and something that dominant horses see as people taking liberties they have no right to, so probably not an appropriate form of reinforcement at the moment, but something horses can learn to enjoy.
Food of itself is not the problem here. But offering - or a horse knowing you have - Something Good without first teaching it manners, and teaching it what behaviours Work to get a reward *& what behaviours don't* is what gets people into trouble. That is why I suggested teaching this from the other side of a fence to begin with and establishing the rules before using them in other 'games'. It's not what *effective* reinforcements you use, but what you teach - inadvertantly or otherwise - with them that causes a horse to learn Good or Bad 'table' manners.