you only get the "new" sign, when there is a new post which you have not read. There isnt any other way to make it new, but the date on the topic will put the topic at the top of the board, so it appears new.
In order to get the latest post at the top of the topic rather than the end, go into your profile and into the section "Forum preferences" and tick the box next to "Show most recent posts at the top"
Not stupid questions at all! Ask away
