Admin has to maintain a forum by "Reply", “Delete”, “Sticky” and "Edit" a post.
If you have a new reply, you will see the icon is not others,
If you have a new post, you will see the green icon in front of its title. If it is sticky, you will see the Sticky tag.
You can reply, edit and stick a post by clicking the ACTION buttons shown in the red box. If you hid a post, only you and the one who wrote this post can see it.