Yeah the volume slider is a huge quality of life option. It would have been nice to allow the player to change volume while in game though. Partheas handled both the volume slider and the credits bear enlargening. He was absolutely delighted by it. Maybe we should include more easter eggs in the future.
I regret making the unaffordable options disabled in the menu. It is unfortunate that you can't see what things cost until you can already afford them. In general I'd probably want to rework the menu entirely.