STR: - go to a playlist or 'My songs' - start shuffle playback of all songs - skip e.g four songs during playback and remember them. - add the fifth song to an existing playlist of yours or 'MySongs' by pressing ' ... ' in playback view and select 'add to playlist' - continue shuffleing songs by skipping to sixth song
ER - shuffle queue continues with randomized play queue
AR - shuffle queue starts again at the first song from already played songs and repeats all previously played songs in shuffle mode ( so in the example above songs 1-5 get repeated). afterwards shuffling chooses again new song to play.
tested on iPhone 6 plus with iOS 9.3.2 and app version 188.8.131.523