When you use the mark all forums read option on the index page (main page of the site) it updates all of the forum entries with your ID to the timestamp at that exact moment. This means that all posts in the database at that exact moment are listed as read.
It has nothing to do with what you have read or not.
Willful ignorance of science is not commendable. Refusing to learn the difference between a credible source and a shill is criminally stupid.
All Contributor questions go to Guru Zim, because I think the whole concept is a loser. But on the other hand, I'm the loser with a website on hiatus and he felt SOMETHING had to be done, so there you go.