I just learned that you can only edit one of your posts if it is the most recent of your posts in a thread. If you add another post to the thread, you cannot edit earlier posts. I'm not exactly sure of the purpose in this, but I discovered it when I wanted to amend an earlier post, put my intention to amend the earlier post in a subsequent post, which made the earlier post inaccessible. (Thank you to the moderators for straightening out the mess).
Also, it would be nice if we could delete our own posts that could come in handy.
Kate