This is intended behaviour. It is standard behaviour in similar applications. I changed it in Scrivener Gold so that it acts how you suggest because of other user suggestions, but on revisiting it I decided I did not like this behaviour. The selection in the binder reminds you of the last selection you made, so that you can return there quickly after navigating through a large number of documents if you so wish. If you want the selection to get updated in the binder, select “Reveal in binder” from the menu that appears when you click on the icon in the header view.