I'm getting too competative, how can i calm down?

Recently i've had an argument with my best friend who told me that she didnt like to be round me at school because im too competative. Admitedly, i do ask her what her scores are in tests to see if i have beaten , but thats because i see her as being the cleverest person i know, she doing better than her is a big achievment for me. I don't say anything to her about it, but she says she can see it in my face and she doenst like that i get satisfaction by putting her down. Its not like that, i dont want her to be upset, i just want to be clever. I never used to be better than her before, but trying to compete with her is really boosting my grades. She says i should try competeing with myself but i have nothig to compete for. I'm predicted As and A*s for my GCSEs, so it's not as if i can aim for higher grades. I found thats its not just school though. WHen i have arguments with my parents i have to be right. Its turned into a sort of winnign thing. If they ask me to do somethign if i say "No" at first, even if i change my mind i cant tell them or else i think im losing. It makes me think that they'll note that down in their heads for future refferences and think im a push over. I have to win: arguments, card games, sports fixtures, better marks in tests, and even stupid things like "who stays up the latest" and "who has the most friends on facebook" etc. Is there anyway i can try to be less competative?