App Store wants me to sign in as someone else?
I'm using a pre-owned computer, but with no identity problems until now: I restarted my computer and when I opened App Store later and tried to update a couple apps, it required me to sign in with the Apple ID of the previous owner. Strangely, I've gone to Store:Sign In/Sign Out several times with my own ID, and up there it says I'm signed in, but when I press "Update" next to the app that needs updating, it still asks me for the Apple ID that's not mine. (Btw, in that pop-up window, the Apple ID box with NotMe@msn.com in it, is greyed out so I can't change it; otherwise I would change it to my own.) I'm having no troubles with my ID on iTunes, so I don't know what the deal is.
Why I restarted my computer in the first place: I downloaded the OS X Mavericks update and it restarted my computer. ...When I was logging back in, it asked me to sign in with my Apple ID, and I did. No problems there...
Please help. 😕
MacBook Pro with Retina display, OS X Mountain Lion (10.8.4)