I have a Mid 2011 iMac.
So here is the issue. Ever since I purchased this iMac (over a year ago) I have been unable to install any updates to iMovie. iMovie came preinstalled with the iMac and I did not purchase it. Whenever I go to update it via the update option on the Mac Store window, I get a message that reads,
"You have updates available for other accounts - To update this application, sign into the account you used to purchase it."
I have only ever used one Apple ID on my Mac, and find no way to circumvent this. Since this came preinstalled on a Mac that I purchased, shouldn't I also own iMovie and be entitled to updates for it?
Edit: More information: I bought it in-store at BestBuy. I didn't create the Apple ID and purchase it prior to going to Best Buy. I created my Apple ID as soon as I turned it on and it either prompted me for an Apple ID, or I just went create one.
When you had purchased the mac. Did you buy it new like at the Apple store for example or as a used mac from lets say a computer recycling centre. If you bought it new then you should be able to update it without a problem. But if came installed and it was not bought through on-line with your Apple ID so it would be recognized as you had purchased it. Then it might be something different.