This week had the opportunity to learn how to configure some other security groups in SharePoint to be the default ones on a given site. Had the scenario where some Site Collection Administrators needed to create beforehand new security groups and assign the members. Then when new sub site was created admin selected the specific security groups, but what happen with the other sites that already exists? In those cases we use the /_layouts/permsetup.aspx page to redefine the default groups.
So, just navigate to the site and use the system page, then just pick and choose the groups you want.