1) Navigate to and click on a thread you're interested in. For instance, on the pope4test forum, click on the thread called
"Eureka! I found 'NEWEST FIRST' listings!"
2) Click on a black NEW REPLY button. It's on the right. If you see a different reply button, don't click on them. They might work too, but let's go with what definitely works.
3) Instead of typing in a post as if you were replying, keep scrolling downward. You'll see one blue bar called POST A NEW REPLY, then a second called ATTACHMENTS and then the coveted THREAD REVIEW (NEWEST FIRST). That's it. The messages following that blue bar are the threads messages in newest to oldest order.