How to reference a sound class and change its volume level?

I want to create audio options. The classic horizontal bar that allows you to adjust the audio volume of your music, sfx, voice etc… So, I’ve set all of my sound cues’ sound classes. From what I understand, if I reduce the volume of let’s say the SFX sound class, every sound cue that has SFX set as its sound class should have its volume reduced.
The problem is, I don’t know how to get a reference to any of the sound classes. I tried with Get All Actors of Class, but they are not actors, so no wonder I see them that way. Are they even created along with the level, or do I have to do something? Are they global objects? I don’t know a lot about unreal’s sound system, let alone the sound class system, but I hope I’m on the right tracks.