The system works on 3 levels. The first is the Topic for discussion, the second a set of discussion threads for that Topic and the third the individual comments.

The V button allows you to view the details in the lower level.

The E (Edit) and D (Delete) buttons allow you to Edit or Delete that item. If you are a Topic owner (creator) you have full access to everything in that Topic, otherwise you only have access to those Discussion threads, or Comments you have created.