Hi Sean,
This is actually behavior inherited from RTC (Team Concert). We experience the same issue using RTC for the RQM project, actually. There is no way to currently edit comments. It certainly can be annoying at times. What we tend to do is use the "comment" keyword, and post a follow-up comment with the correction, i.e. "in comment 5 I meant to say" where "comment 5" will turn into a link to that actual comment.
There is a "secret" administrative way to delete comments but I have not actually used that yet and am not certain how to do so.

Regards,
John

Is there a way to Edit the comments that are already stored against a requirement?

I am only using the RQM Web front-end, and the only action I have available is Add Comment.

So my workaround for now is to create new comments that quote previous comments (according to user name, date and time), and provide the correction. Much like that of a forum post.