Hi all, I have a really weird problem. Actually, it's my friends problem and I'm involved. Since I think it's easier to understand from her point of view, so I'm going to write it that way! I am trying to use Mac App Store to update my 10.9.5 to Yosemite. I am logged into the App store. When I click the download/install button for Yosemite, I get a message asking me to log-in to my account. Not a problem, except that it is my friends ID which comes up and I can't seem to change it. Neither of us have any recollection of ever logging into the account on either of the others computer, but somehow this is happening. The further difficulty is that the App store won't let me log out or change the ID in that field so that I can use my own ID. I appear to be logged into my own ID in the App store, but when trying to do the update, this new problem happens. Can't make sense of this problem in any way shape or form. There is this part which is somewhat interesting, but I can't seem to make the connection to the current problem: I was in a communal living situation in November where the DSL connection was a slow-medium speed. There were about 10 of us who wanted to upgrade to Yosemite, so instead of taking 5-10 days to download the 5GB for each person, one person downloaded it and distributed it. I am one of the culprits who took advantage of having the file, but with this caveat: I NEVER used it, just took the file in transfer over a USB stick but never installed it. I'm checking my "About my mac" section and I see I'm running 10.9.5 which means I never did use the file. That is the only connection I can make to the problem I'm having, but even that doesn't make any sense! As an aside, if anyone can help me remember what Mac thinks the installer file is called, that might help me, too. I think it was called something like "Install Mac OSX" or something, but I'm not sure. Thanks!