Grats for making your first game.
So for the music issue. I think you are using Audio2D. This plays on 1 side of the ear. Make sure you use the regular audio player, not the 2D one. Or it's an import setting.
There is also the stutter between changing scenes. (I have this issue as well, would like to know how to fix this for HTML5 imports, seems to work fine of Windows).
I picked up 2 other things.
The attack defaults to the left side. I think what would have been great is if you made a variable to store the position you were moving and then base of the attack off that.
In addition, i would add the change scene for the ghosts a bit closer to the edge of screen. For about 10 seconds i thought the game was bugged.