The way you need to think of this issue is it is like moving to a new host.
All the forums are stored in the database. So all you do is just edit the config,inc.php file to point to the database as well as the user and password.
I have no clue on what you mean by drop down.
Unless you have collapsed a category on the summary page.
But it appears that you had a browser cache issue and figured it out.
