Apologies if I’m the only one that did not know this.  I sent a note to Ben Strano complaining that the FW search did not return Discussion Forum items.  Ben replied that was intentional but there is a separate search for the Forum.  I found it with his help, but you have to dig for it.

Click on the main menu (3 horizontal bars) on the top right of the main page
Scroll down the page and, under the More item, click on Forum
The search icon is on the right side of the main menu bar