Each topic thread has some navigating tools.
If you are at the bottom of a long thread, the easiest way to get to the top, is tap on the number of posts (in the blue rectangle) and use the slider bar, or the “jump to” to get up to the top post.
While you are reading through a post, you can see what the poster was replying to, by tapping the “replied to” icon.
If you have any other navigating tips, feel free to post them here. 