iTunes Store

I have been using iTunes for a long time now and I'v always have had pretty good luck with it but right now I am trying to buy songs and its not letting me. I have money on my account but everytime I tried to buy music it takes me to my credic card info and thats not what I want. I'm not sure if its cause I'm not at home but Im using my laptop that I keep all my music on. Please help! Thanks.