Switching users when using Team Foundation Service & Visual Studio

I encountered this problem using Visual Studio 2010, but it might also apply to Visual Studio 2012, Eclipse & Team Foundation Everywhere. It's relevant only to the Team Foundation Service, not Server (for the server, the secret is to clear the "Credentials Manager").

I wanted to switch users, but I could not. Long story short, when I tried to log out I was automatically logged in, when I tried to open my other TFS site I got error TF31003 with the "Use different user" link missing.

The solution:

1. Close all programs.
2. Open "Internet Explorer".
3. Click on "Settings" (the wheel on the right side in my version of IE).
4. Under "Browsing History", click on "Delete", select "Passwords" and delete.
5. Next time, NEVER EVER click on "Sign me in next time" in any of Microsoft's services.

TFS Error: HTTP code 403: TF53011: DOMAIN\USER is not a licensed user.

While adding a new user to the TFS I got the following error:
HTTP code 403: TF53011: DOMAIN\USER is not a licensed user.

There are many talks in the web, but the solution might be VERY simple (it was in my case):
Add the new user to the TFS group "Team Foundation Licensed Users Group":
- In the 'Team Explorer', right click on the TFS Server -> Team Project Settings -> Group Membership
- Add the new user to the following group:
[SERVER]\Team Foundation Licensed Users Group