It's unclear to me how I can modify pieces of the wheel that have already been set. D:

Go to C:\Users\YOUR USERNAME\AppData\Roaming.minecraft\config
in the minemenu-common.toml (open with a text editor) you can change the option "rightClickToEdit" to true.
or just change the whole file to this:

[general]
toggle = false
rightClickToEdit = true
releaseToSelect = false
menuAnimation = true
menuButtonIcon = "minecraft:stone"

[visual]

[visual.menu]
	#Range: 0 ~ 255
	alpha = 153
	#Range: 0 ~ 255
	red = 0
	#Range: 0 ~ 255
	green = 0
	#Range: 0 ~ 255
	blue = 0

[visual.select]
	#Range: 0 ~ 255
	alpha = 153
	#Range: 0 ~ 255
	red = 255
	#Range: 0 ~ 255
	green = 0
	#Range: 0 ~ 255
	blue = 0

Or just press shift

Thanks for explaining it @AstragoYT
The path mentioned above is only correct if you have Forge installed in your vanilla launcher. "minemenu-common.toml" will be located in the config folder for whatever installation you have - depends on the launcher.