>Now, when I log on I'm seeing all messages from the last few days (maybe since the URL changed ?) rather than just those that were posted since I last visited.......

I see some of your access have been done in anonymous mode. That would generate that exact behavior. Then, I see you logged in. And, that would recognize your account and the relevant settings, thus the last pointer of the last read messages.

I would suggest to add levelextreme.com in the list of trusted site.