Hi thanks for the reply (I am not sure my silly posts deserve your attention tbh!).
Anyway, I can see how you are right. You know, a 'mark forum read' (that marks every post in every thread read) and/or the same thing for thread only would be jolly nice.

I figured out what was causing my read posts to become 'unread' anyway. Its because I have more than one forum installed on the same domain - one is 'live' and other is 'developing'. Every time I logged in to my dev forum it must be overwriting the cookie for the domain and resetting all the posts on the live forum's Latest Postings box to blue. Derp!