How can i get my horse to respect pressure off my leg?

i am part of the Parelli natrual horseman program with my 13 year old QH he is great and interested doing the games but whenever you get on him he is mad and almost affended and any time you ask him to canter he cow kicks...What can i do to have him respect the pressure from me. i do not put tons of pressure at a time either i do step by step..... tell me what u think?