For some unknown reason in AppStore on my MacBook Pro after completing the Yosemite upgrade I encountered the following issue. There were a couple apps which required updates which were performed as expected. But, two apps requiring updates, iMovie and iPhoto, when trying to update them needed the required password for a specific email account of mine. It's not the email account I've ever used for Apple services, just a junk/all-purpose kind of email. The email field was greyed out so I could not modify it, and I'm absolutely certain I've never used it for Apple services. As a result, these two apps remain at the current levels. Is this resolvable and how? What's happened here?