Ok. Let's see if I can explain this so you understand.
I once had a iPhone. Had iTunes on my pc which is up to date. I no longer have the iPhone but kept iTunes. Now I have iPad 2. When I registered it I used a new apple ID .I synced my pad to iTunes but I can't get rid of the old apple ID on the apple store on the iPad. I can purchase new but can't update because it comes up with the old apple ID. I checked AppStore in the setting and It shows my new ID. Im thinking maybe I have to delete all the apps that show that have updates and reload them. Does this make sense to you.. I hope so.. Thanks in advance