What has been read

Is it just me? Do I have some queer setting on my browser? When I enter the message board all messages are marked as unread, even the ones I have already read. When I go to a thread and read the post and then the first response all the responses are marked as read and I can not really tell which ones I have already read. Then if I have to go and come back into the forum later all the threads are marked as unread. I hope it is some setting on my computer that someone can instruct me on changing, because I am getting frustrated reading posts twice and missing info that I think I have already read. Please advise...