How to change the iTunes Store BACK to the American one?

Okay I saw a SHINee song on Twitter and it had the link to buy it on iTunes and it turned our I couldn't buy it because it was a Japanese song. So this thing popped up that said "do you wanna change it to the Japanese store?" (or something along the lines of that) and I pressed yes. I was going to buy the song but I completely forgot about it. And now I can't change it back! I can reach iTunes and the App Store through safari on my iPhone but I can't use the actual apps themselves to download anything?

1. Open iTunes.
2. Scroll to the bottom until you find the "Explore""Features""Help""Manage". Click the Japanese flag Icon.
3.In the page you can choose your country or region.