is there any way to mark all read on exiting forum?

(other than having to do so via forum tools)

You'll have to go to Quick Links - Mark Forums Read right before you exit each time. There are many forums here I don't go to - it doesn't bother me that I've not read messages there. For the ones that I do visit, I like having the ability to leave and come back and they're still marked as "unread" if I didn't get the opportunity to look at them this time. Other than manually doing it, I don't know how it can be done.

It appears it automatically happens after about 10 days anyway.

There's also a link to "mark all forums read" near the bottom of the main forum index page.