Hi when I click mark forums read it still shows me all the previous posts any ideas?

Uuread posts on the forum are shown in bold writing

When you mark the forum read, all the posts go to standard non-bold font, but will remain visible for future reading

When you leave the forum and return, any posts that have been updatedsince your last visit will again be in bold

Leave and come back without having read them all and anything that was unread on your previous visit is still in bold, as well as any further new posts

If you mark the forum as read before you leave every time, then when you come back, again, only new posts since your last visit will be in bold