I've noticed that the new forums doesn't track and display which threads you've personally participated in like the old forum did. This forum only displays threads that have new posts within them. Is there a way to fix this?
Since the revamp, you might have to go back in to your USERCP, then click General Settings (it is on the left hand side, under the "My Account" section. From there, scroll down to the "Default Thread Subscription Mode:" and choose your option.
You can also subscribe from within a thread by clicking the "Thread Tools" at the top left and then clicking "Subscribe to this thread..." and choose the proper option.