Manually reset cookie domain?
 

I am trying to setup a copy of my forum as a test server, but I can't log in to my forum. I uploaded tools.php and the cookie domain is still my old domain, but I can't reset it from there. It says "Processing Complete -- Proceed" when I click the link to clear it, but when tools.php reloads it still has my old domain as the cookie domain.

I posted this support question on vbulletin.com and was told I could reset it through the database, but I don't know how to manually reset it in the database and nobody responded to my inquiry there. I've also searched and found several people saying modifying it through the database worked when tools.php failed, but nobody explains where they made this change. I'm hoping to have some better luck here - can anyone tell me how to do this manually?