If the thread is bold and highlighted, clicking on the thread title should take you to the last post read.
As far as the forum is concerned, this can be literally be the next post you have haven't read (if you have read the thread before), or the next post from when you last clicked 'mark all read' in your home page.

If the thread isn't highlighted, clicking the thread title will take you to the first post in the thread.


If you specifically want to go to the first post, click 'all' if it's a multi page thread, and you'll get every single post in the thread!