I think that is just a feature built into the forums. There doesn't seem to be a setting for it as far as I know. I think it just marks them as read if you have been on the site for an hour or so, and it has always done that.
You can still quickly see recent threads in the module on the lower right of the main page here:
http://www.eqemulator.org/
I normally just scroll down the index and look at the dates for any that say Today or Yesterday or whatever date.