When i jump my 6 year old gelding at home he is  a great jumper but at shows he jumps really high is it because he is really exited because of the other horse and being off the farm or what? I am very Confused with him.

How high are you jumping him? A lot of green horses tend to overjump. If you pracrice gymnastic exercises, it will help inprove his form.

And I like to think that it is better that they're being careful and jumping "too high" than not jumping enough. :]

He's just overjumping, it's a greenie thing. Basically you want to set up exercises that are going to cause him to jump across the jump rather than straight up. Setting up a plain single with a ground pole then bounce stride to the single, then a landing pole. You can also set up gymnastics, with a few oxers thrown in for some width.

i am jumping about 2'9 he is getting better at home jumping more across then up but he is still over jumping at shows but i agree its better he overjumps than dosent jump enough..