First lets go over some of the icons so you know what they mean.

  This icon is for forums that have no new topics or posts.

  This icon is for forums that have new posts or topics in them. The forum names will also be in Red Text, this is new.

  This icon is for an announcement that you have already read.

  This icon is for an unread announcement. The topic title will also be in Red Text, this is new.

  This icon is for a sticky that you have already read.

  This icon is for an unread sticky. The topic title will also be in Red Text, this is new.

  This icon is for a topic that you have already read.

  This icon is for an unread standard topic. The topic title will also be in Red Text, this is new.

  If any of the topic icons have a red dot in them, it means you have posted somewhere in that topic.