How can I edit comments on Facebook?
When you comment on your friend’s status, photos or link, and want to edit your comment, simply press the ‘X’ in the top right corner to edit it. Your comment instantly turns into a text box where you can alter what you’ve writer, then just press Enter again to save it.
Note: If someone send a comment after you, your comment will be blocked, but you still able to delete your comment by the same ‘X’ button. Also you have to know that you also have only 60 seconds to edit your comment.