Currently, there are no ModMenu config file support. And, as I see in files, there are no config at all.

Also seems to happen on Fabric...
It's kinda hard to diagnose this kind of bug, but I'll see what I can do to fix this in the next MidnightLib update.

There is a config and it should automatically get registered using MidnightLib, but it doesn't work with the quilt version for some reason.
While I look into this, you can go into MidnightLib's config and set "Config Screen List" to "Yes". Then, you'll be able to access VisualOverhaul's config from the Options screen.