Unless you're using a fuzz that's particularly sensitive and you use your guitar volume knob to clean it up, just leave it at default. If you use fuzz, I assume that would be first in your chain (so first block), or if you have other pedals, if you use fuzz it would STILL be the first in the chain, even if it's not the first block (first enabled), but otherwise 1M is perfectly fine.
I've used Helix gear for a decade and never once bothered to mess with this setting. Not a big fuzz guy, admittedly.