Serato DJ considers a track played if you have cross faded to the track and brought the line level fader up. If you don’t do both these actions, the track will continue to stay unplayed or “white”. If you have played the song and then ejected it, it will become a played song, go “grey” or "blue" (depends on the played track color settings) and be listed in the history. You can choose to show tracks which you have auditioned, but not actually played, by checking the show unplayed tracks box. The session will then also list these tracks in grey, along with actual played tracks.
Alternatively, you can mark or unmark tracks as played manually. Select a track (or a group
of tracks) and click the mark played / mark unplayed button. This may be useful if you play a track off regular vinyl or CD - (breaking the A-B algorithm).
Tracks that you have played are marked as grey or blue in your library. Click on the button marked reset to clear the list of recently played tracks and turn the color of your library back to white.
NOTE: 4 Deck Serato DJ hardware will display decks 3 and 4 in the History panel.