After around a day, topics become 'unread' all by themselves, even though nothing has been added. (Title in bold typeface)
it happens whether I log out or not.
so the unread status is stored in my browser, and not on the server? That's a strange way to do it. There is no [mark all unread] link, but even if there was, why would I want to click it. I don't want them marked unread. I want the ones I've already read to be ... read. (??)
It stores info in both places (browser and server). And yes, this depends on your login/logout stats. it starts tracking your read topics when it detects who are you. So you should be login to let forum know who are you.
The button is here, and I recommend click it to reset all incorrect things.
You should turn on the footer statistic to see it.
Yes, I'm always logged in, so it should know that I've read the topics. It just seems to forget the read status of all topics after a day or so. Admins have not turned on footer statistics.
other members experience the same thing
Because this is a user and website specific issue, we cannot provide other debugging ways and solutions. So using that button will reset the logs and may stop the issue. This is not a general issue, this is not a bug, and we don't have any other ways to help you.
I'm sorry, but we cannot debug each line of codes in your website and plugins you're using, this may be a conflict with other plugins or server specific issue. In any case, this is out of our support, for sure.