There are no unread threads vs. Sorry, There a no new threads to view
 

If I log in as "administrator" and search new posts (with forums marked as read) I get the message:

Sorry, There a no new threads to view.
you may search for threads updated during the previous 24 hours, here

If I log in as "registered user" and search new posts (with forums marked as read) I get the message:

There are no unread threads.

What setting do I need to change so that registered users get the same message as the administrator?

You can change it in the Phrase Manager in the ACP.

Change this vB Phrase to whatever english translation you would like.

no_unread_threads

You can also search 'There are no unread threads.' and you should be able to find it even easier.

I've already searched both vbulletin.com and vbulletin.org and came up dry. :(

I could always change the vB Phrase manually but I'm under the impression that I shouldn't be getting the "There are no unread threads" message to begin with. I'd hate to start making manual changes if other options are available.