iPhone and apple ID

When I try to update a certain app on my iPhone 4S, a window pops up saying to enter my Apple ID password. The problem is, the email that comes up in the window is not my Apple ID password. I've checked it in the settings, and it is correct.

What would make the wrong email address pop up in that window? How can I correct this issue?

Thanks for any help.

Did you purchase your iPhone 4S from someone else and not new? If you did, it might still be reflecting the former owner's Apple ID. What you would need to do in that case is reset the iPhone from iTunes and then enter your Apple ID and password. Make sure you back it up first before resetting.