For me, the system keeps track of my last post read on any thread. There are indicators in the New Subscribed Threads
and View all Subscribed Threads
in my User CP. By hovering over this indicator, you will see that you can be directed to the first unread post in that thread.
I've attached some examples of where I can look for new posts. These indicators are also in your New Posts
and at the forum level, placed just before the thread title.
Is this what you need?