When I try to purchase coins for Jackpot I'm told I have to leave the German store but my account shows the US store, what can I do to change it?

I used the German store to purchase a song. I've tried to switch back to the US store and my account shows that I have, but when I try to purchase anything I'm told that I have to switch back to the US store. If my account shows that I'm with the US store, where do I go from there. It's making me crazy!