When you view a thread, if new posts are shown at the top with older posts underneath, you can change this to show oldest posts first by doing the following:
* Make sure you are logged in
* Then
Edit Options
* Scroll down to the
Thread Display Options section
* Edit the
Thread Display Mode to
Linear - Oldest First (see screenshot #1 below).
If you've been following a thread and you want to jump to the first
unread post in a thread, click the green arrow on the thread listing (see screenshot #2 below).
Cheers