Thanks, Mike. I just found it and enabled it. I tried it out, but a message appears at the top of the screen stating, "added to multi-quote." What does this mean? I apologize, on my old forum (phpbb) "quote" brought you to a new reply section, where you literally quoted another member's post.
The functionality you're looking for is simply the reply button. Multi quote is a helper for the situations where you want to reply to multiple messages. It adds a button to the quick reply area to insert quotes for the messages you chose.