UBB.threads PHP Forum Software Community Forums UBB.threads 7 Version 7 Support dumb question: can't figure out "mark all read (in forum)"

https://www.ubbcentral.com/forums/ubbthreads.php/ubb/cfrm <-- for this board..

now look at the left hand side.. you have images there.. the yellow ones mean 'unread'

just double click on the yellow image and *poof* marks THAT forum and it's sub-forums as read