There are a couple of things you can do to edit your sticky notes to better accommodate your songs.
1. You can pinch the sticky note on your song to make the sticky note's scale smaller, or you can expand your fingers to make it a bit bigger if you accidentally make it too small.
2. While editing the content of the sticky note, you can tap the A icon next to the Done button and adjust the font size or scale of the sticky note from here.
3. Additionally, when in this dropdown menu from the A icon when editing a sticky note, you can swipe right on the Note Color section and tap the last color before the + button to make your sticky note transparent. That means that you can write text on the sticky note but still have your song's content shown underneath the sticky note.