[answered] Very Quick Question!

You can only edit up until the time another person responds to your post.
We used to be able to edit past that time, but the process was slowing a2k down.

You can only edit posts that have not had replies. At one time you could, but I believe that there was a problem where people would change their mind about something, edit or even remove a post, which caused a lot of confusion.

Hint: Check out the "Preview" button before posting. I have caught a lot of boo-boos in my posts that way!