Until yesterday (when I couldn't make it work) I would go to the very front of the forums, switch my preferences to California Gold, and Search would work. But that didn't work yesterday after I posted about it.
So the other options are just scanning the pages for a subject line that seems helpful, or using Control F with a search term (scans the page for you), going back page by page, OR googling "disboards" + what you're looking for.