A post is marked as "seen" when you actually have a look into the thread. Afaik no shortcuts to mark a complete forum. But when threads are too old they are not considered as "new", although the counting of the number of posts seems to be a bit... well... I didn't find out yet the base of numbering system.
Searching (and finding what you search for) is a theme... A working solution is to use the Cypress Document Manager which has a lot of checkboxes to specify what exactly you are looking for. Quite a good help!
PS: When looking out myy window all is WHITE! Heavily snowing! Temp -3° C
Thanks Bob - good to know I;m not missing something.
PS: quite a cool 25 here at the moment - its a bit of a cool patch in between the 35-40 degree heatwaves. (I was going to mention the bush fires around here that burned down 116 houses on Christmas day but I hear there are wildfires in California as well - go figure!)