[nerbert]

When thread is marked read the threadid, userid and read time are recorded in the data base. This product simply deletes that entry based on threadid and userid.

I haven't followed through all the code but I would assume a year old thread isn't shown in New Posts simply because search.php searches back only so far (the seven days you used for an example). So to show a thread older than seven days you would have to build a special table to store ancient threads marked unread and append that list to the New Posts search. It's doable I suppose but far more work than I want to get into.