Back button does not play previous song in Apple Music

When I am playing my playlist on my MacBook on Apple Music, and this song proceeds to the next song, I sometimes hit the back button on my keyboard to just repeat the song, but for some odd reason, it plays a completely different song, and when I continue to hit the back button, it starts to play songs that I never even listen to yet. What is the issue? Does anyone else have this problem?

[Re-Titled by Moderator]