I replied to the QuickBooks team's posts on this with a similar question but, to answer your issue, I've found that there is a section in the registry at 

HKEY_CURRENT_USER\SOFTWARE\Intuit\QuickBooksCommon\QBFinder

where you can find the recently opened files. Perhaps you can check each individual users keys, and edit those to the correct info, or even delete (first backup) the keys with the old server info.