If I right click on a selected sim I only have the following options : Enhance - Select as Best - Remove
OK, sounds like you're not logged in, or that the sight had trouble with your login information, or that there was a "tutorial" issue.
The single sign-on that the Zoo projects and the forum shares should work fine, but one way to check if that is your issue is to logout and then try logging in again directly from the mergers home page mergers.galaxyzoo.org
. Again it shouldn't matter where you login, but it might have an impact in your case.
The other thing to check is to make sure you haven't bookmarked the applet page directly and that you launch it from the menu at the top.
If you're still not seeing that option, then it is possible that there was two other issues. One being related to single sign on, the other related to the tutorial.
If you launch the applet with out having "completed" the tutorial, it will still be in preview mode. To "complete" the tutorial, you have to first go to the How to Take Part page and click on the link that says "Click here to Merge Galaxies with live data". If this was your issue, though, there should have been a flash message when you loaded the applet reminding you to complete the tutorial. We should probably make that more obvious.
The "New To Mergers" button on the home page takes users to the How to Take Part page.
I'm so sorry for not making this more obvious to returning professionals like you
from the beta site. The flash message probably isn't sufficient to communicate this to people who are already familiar with the beta site. Honestly, expert galaxy colliders like you already know the main functionality of the system, and I totally see why you would want to just get to it.
If this still doesn't help your issue, then let me know via personal message and I'll work with Arfon to double check your account is configured correctly in the database.