I just discovered a setting which makes Unread more like what I prefer. I was able to turn off tracking for threads I just read, not posted in. Go to your profile, select the drop down menu that currently says Account, and select Notifications. Under “Consider topics new when” select “created since I was here last”. Under “Automatically track topics I enter” select “never”. Under “When I post in a topic, set that topic to” select “tracking”. That should render Unread to topics you posted in that have new posts since you were here last.