Hi everyone. I have search the guides and forum for 2 days and can not find the answer.

Currently. My forum requires everyone to either sign in or register. You can not see the site otherwise.
I want to change that.

I would like the site to be viewable by unregistered guests/anyone who visits the domain.

If they would like to post? Well then they have to register.

My problem is:
I can not find a setting that adjusts my forum to these wishes.

I swear I saw a check box to deactive mandatory registrations. 
Can anyone help? Thank you.

Most likely you're not allowing guests to see the forum. Check the setting in "ACP > Members > MEMBERS > Groups > Guests > Edit (pencil icon) > Can access site?"

It seems you already have that set at present. Have you changed that since?

Thanks for the help everyone. Wanted to update that the fix was in the Group settings for Guests to be able to view the site.

Thanks so much. Forgot to follow up.

Glad to hear you got to where you needed there 🙂