How do you change your iTunes account on your iPhone?

You can't. I am presuming you mean your account. No you cannot. You must go to your computer and open iTunes up. Then you must go the iTunes store. Log out and log in with the account you wish to use. Then make sure your iphoneb is connected to the computer. Once that's done, sync your iphone with the computer and the account will change.

OR YOU CAN.....

Go to Settings > Store and tap "sign out" Then sign in with the account you want to. This is on your iphone not your PC.

On the iTunes Store page there is a Sign In button below the search box in the top right corner. Click on the button and fill in the account details.

I have ocd and my app store button kept telling me there was an update for facebook. Every time I went to update it I was asked for someone elses passWord to match their email. I tried signing out of Itunes on my computer and phone. I finally assumed the facebook icon was an old app someone else installed on my phone. I reinstalled facebook and everything was fine after that. Just in case the previous responses didnt help.

Note: changing the userID on the phone WILL NOT retain the purchases, i.e., songs, apps, movies. They are LOCKED to the account and there is no way you can legally transfer them to the new account. They will be deleted when you change the accounts. When you change the account back, the purchases will return.