Reader Jack Sanford is being lied to by the Mac App Store and would like to do something about it. He writes:
When I checked for Mac App Store updates on my MacBook Air, it said there were no updates available. But when I clicked the Purchases tab, the button next to iMovie showed Update. I clicked that and got a dialog telling me "You have updates available for other accounts." But I have only one Apple ID that I use for purchases. How do I fix it?
Developer and all-around-smart-guy Brett Terpstra has the answer you seek. In his Quick Tip: Fixing the "Other Account" Mac App Store Issue he explains that you can clear up this fib by first repairing disk permissions and then rebuilding OS X's Spotlight index.
To do the first task, launch Disk Utility (/Applications/Utilities), select your startup disk in the window that appears, and click the Repair Disk Permissions button near the bottom of the window. In a couple of minutes your permissions will be set right.
Once that's done, launch System Preferences, select Spotlight, click the Privacy tab, and drag the icon of your startup drive into the list below. Click OK in the "Are You Sure?" dialog box that appears to acknowledge that you really want to add your drive to the list. When the drive has been added, select it and click the Minus (--) button below to remove it. Yes, it seems to be much ado about nothing, but in fact this causes the drive's Spotlight index to be rebuilt, which, in turn, solves this issue.