If you're still having difficulties with finding the last post, try this:
"Jump to last post in Pprune mobile thread?" This is the title box.
To the right of this, find a light blue rectangle with the date, time, and the name of the poster; just to the right of his name, there's a blue square with a white arrow inside it: click on the white arrow; that takes you to the last post.
Cheers.