A change was recently added that causes the first new post in a folder to be selected when you select that folder. The problem with this is that selecting a folder now has a side effect of marking a post as read. That means that if I click a folder, then click a different folder (like if I change my mind about which folder to read first), a post has now been marked read, and I have to do the whole process of changing the setting to see all posts, etc, to be able to go read that post. In attempting to save me one click, this new feature has already cost me at least a dozen.
Sure, just turn it off. Manage > Preferences > Feeds > When opening a site, show all stories.