Cannot change Apple ID in App Store for downloading Yosemite

Question

I want to download the latest version of Mac OSX (Yosemite). But, the app store doesn't let me change the user id for authentication. Interestingly, I don't know whose apple ID is prepopulated into the text box. I have used my macbook all by myself until now!

I tried to logout and login again. But didn't work. Does anybody know how should I fix this and download Yosemite?

Solution 1

The Problem is the way Apps are tied to IDs.

A step-by-step guide to solve this problem:

1. Go to the app listed in the App Store as needing an update (usually in the /Applications folder).
2. Right click the app then click “Show Package Contents”.
3. Go into the “Contents” folder, then into the “_MASReceipt” folder.
4. Delete the “receipt” file (you may need to enter a local administrator username and password).
5. Please note that the app will still work as intended.

Theres a pretty good explanation in here: http://www.valiant-ny.com/2014/06/grayed-out-apple-id-explained/

Solution 2

In the MacAppStore's task bar go to Store and then log out. Then try it again.