This is a quick and easy example of how you can make music evolve as you go through a menu. How does it work? Instead of putting an effect on the music using Scratch, I have both the original song and the version I put a low pass filter on. They both play all the time to keep in sync. I use the volume setting to have one muted all the time, and to cross fade between them, I have one fade out and one fade in in sync.
lol had it sitting in my unshared projects and thought I would share updated on 2/22/24 because i felt like it (added slider)