Most forum sites have a way to mark all posts as having been read, but I cannot yet find this facility here. Is it hiding somewhere I have not looked, or is it missing from this site?
For this site the volume of posts is low enough to just go through threads with new posts from the top until I get to the first one I have completely read which is marked by the title being in a slightly fainter colour.
Although a “Mark all topics read” feature has now been available for some time, I find that I almost always have to select it twice to clear all the unread thread marks.