Upgrading to TestExecute 12

We've updated TestComplete to version 12. We have an instance of Test Execute 11 running on the build server. I've read in somewhere that TestComplete 12 tests are best run in by Test Execute 12. How do we upgrade to Test Execute 12?. Every time we open it we get the message that a new version (12) is available but the then there is another message saying that "There is no new versions available".