Almost all of the music elements in Syrinscape are a collection of pieces of music appropriate to the soundset. When you click a mood or just the element it will play through the pieces of music contained in that element. You can double tap the symbol next to the elements name to make it play a different piece of music but you can not select a specific piece of music from within that element.
A small number of soundsets have elements that contain just one piece of music, these elements show the name of the song and when activated will just play the one track on repeat.
In the case of Witchwood the top two elements “music (long delay” and "music (no delay) both contain multiple musical scores. The five elements below those, for example, “Music (Darkelf Harpist)” are single pieces of music and will just play the song named in the elements title.
Does that make more sense?
To make Syrinscape play the music you want you need to either only use the elements that contain one song like the “Darkelf Harpist” example above or build a soundset in the Syrinscape Soundset Creator where you have built different elements for each song that you want.