Today for some reason whenever I refresh the site I got unread notifications for threads I’ve never read before and ones where I only bothered to read the first post of. I don’t know if this is a bug or just something with my preferences
Go to Preferences > Categories or Preferences > Tags, check if you have any Categories or tags listed as Watching
there’s nothing there, but the notifications have seem to have stopped for now.
I don’t know about threads you’ve never clicked on before but if you’re on a thread for a while it’ll swap it from “Normal” to “Tracking” with something along the lines of a message with “You will see a count of new replies because you have read this topic”. There’s a couple of settings to change that. It’s determined by how long you were on the topic I believe.