We share three iTunes accounts on our home desktop. Each account is linked to a different iPhone.

My phone (4) was asking me for my apple ID password multiple times a day and would never connect to the App store so I could download updates.

I followed another post's advice and rebooted after logging out of iTunes. After turning the phone on again, and logging back into iTunes, my phone shows that I am logged into my sons iTunes and wants his password. My settings clearly show that I am signed into iTunes, but the pop up window says it's my son's logon.
My home desktop is also logged into MY account, not my sons.

Why is my phone insisting it's logged into my son's Apple ID? How do I get it recognize MY ID?

Any help is appreciated!