Reply to individual after accidentally just replying to thread

I've found that if someone replies to a suggestion I made by hitting the reply button at the bottom of a thread, I won't get a notification. I will get one if they hit the reply button next to my comment, however. Maybe I've misunderstood how this works, but I often find myself manually trawling through my activity list to see if people still need help.

I sometimes forget too, and wonder if I'm not getting a reply to the suggestion I spent an hour on because people aren't getting notifications. The only thing I've thought to do is to edit my comment and @ them.

So I have two questions:

  1. Am I talking out of my arse?
  2. Is there a way to change a general reply to a personal one after the fact?