App Store ID is not mine. How do I change it?

Question

Someone else's ID has replaced mine when I tried to update some apps from the App Store on my Mac. There is no way to delete it that I can find. I’ve quit out, reopened APP Store, logged into my Apple account no problem, but still can’t get rid of the wrong ID. Even deleted all the .plist files I could find—still the wrong ID shows up, which is grayed out.

Answer 1

At least one app was installed with the Apple ID you don't control. You need to identify and remove that app.
Important: The app you need to remove may not be the one named in the update notice. For example, the App Store could prompt you to update "Angry Birds" or "Twitter," but the app in question could be "Final Cut Pro." Don't make any assumptions about which app you're looking for. To find it, you must carry out a systematic search with Spotlight.
1. Triple-click anywhere in the line of text below on this page to select it:
kMDItemAppStoreHasReceipt=1
Copy the selected text to the Clipboard by pressing the key combination command-C.
2. In the Finder, press command-F to open a search window, or select
          File ▹ Find
from the menu bar. In the search window, select
          Search: This Mac
from the row of tokens below the toolbar. Below that is a popup menu of search criteria, initially showing Kind. From that menu, select
          Other...
A sheet will drop down. In that sheet, select
          Raw Query
as the criterion, then click OK or press return.
Now there will be a text box to the right of the menu of search criteria. That's where you enter the raw search query. Click in that box and paste the text you copied earlier by pressing command-V.
3. The search window will now show all the App Store products that are installed. Compare those search results with the list of your purchases from the App Store. To see the complete list, you may need to unhide hidden purchases. If any apps were download from the App Store using other Apple ID accounts that you control, sign in to the store under each of those ID's and check the purchases.
4. At least one of the apps in the Spotlight search results is not among your purchases in the App Store. Move each such item to the Trash, after quitting it if it's running. You may be prompted for your administrator password. Empty the Trash.
5. Quit and relaunch the App Store. Test.
If you find these instructions confusing, ask for an alternative method.