edit: I withdraw my original suggestion.
This is my improved suggestion:
Keep the user group called everyone, but disassociate it from guest
However, if you feel strongly enough about my original (or think it's a better idea), it is below.
To me the user group labeled, "everyone" is like having a 2nd "guest" group.
I basically have to uncheck everything twice (2x) to prevent guest from posting or doing things they shouldn't be allowed, because even when you tell the "guest" group, no, the "everyone" group may still say, yes.