New Post disappear

[Gimme Time]

OK, Need help. Very often when I log on and open a thread such as the Trailering one I'm asked to click on a light blue line (don't know what you call it) that takes me to another area such as the boat trailering test. Take the test and come back to CSR and now the site shows post read rather than still highlighted a unread yet? How come when I come back to CSR all the forums are now shown as if I've already been read?

Sorry if this is already answered on the FAQ list but I didn't see it if it's there!

John