Should User Groups be checked at products?

Hi,



I have not create any user group. I have only the Administratos under the user->user groups.

So any user creation through my site, creates a customer.

The weird thing is that in the general tab of the products, the availability->user groups says : All - Guests - Registerd.



I did an “edit selected” for all products and checked the all option, but for some reason it is unchecked again? All the customers functions seem to work fine ! As registered user or as guest.



Should this box be checked under my group situation or not? And how important is this checkbox?



thanks