When you comment on a topic and use the quick reply box at the bottom of the page, and want to keep up with it, make sure the "watch this topic" box is checked.
If you click on the reply button, you will automatically be watching the topic after replying.
To find the topics you have elected to "watch", click on My Watched Topics at the top of the screen. It will show a list of all of the topics you are watching.
After you read a watched topic, it won't reappear on the list until someone else comments on it again. :D:D:D