When you exit and then relaunch Traktor, the browser remembers what your selection was in the Track Collection section of the side panel (say All Tracks) but the it does not remember what column was sorted when the app exited.
Ideally this should also be restored automatically for you. I like to have All Tracks sorted by Import Date for example and in the current build, I have to resort the view correctly every time.
This works in the Playlist section btw.
Thanks Traktor peeps!