If I visit a section, there are some thread titles that are in bold, indicating that there is new content. Other thread titles are not bold, indicating there is nothing new for me to see. On the bolded titles I can click the blue box with the "down-arrow" to the left of the thread title and it will take me to the first unread post in the thread.
On any other forum, if I walk away from my computer for a few hours, days, years.... and refresh the page, then any threads modified since I last looked will be in bold as well as
all the threads with unread content before I walked away. Here, however, after some time the forum software will decide to mark everything read for me even though I have not read everything, meaning that any threads I intended to come back to are no longer highlighted, and -- most annoyingly --
there is no blue box to click to take me where I left off reading. My "place" in the thread has been lost. I have to either search to find what's been added since I last looked (on long threads that could take a while) or give up and abandon the new content added between the time I left and the time I came back.
I hope this makes it clearer.