@yariplus Great thanks for these insights.
Actually I see two types of groups:Settings > Group (in our case these are Guests and Registered-user for example) Manage menu > Groups (in our case these are Ambassadors and Administrators for example)
So when I manage the category I can only manage the first type of group but not the latter that interests me the most.
For example, I wish I could have a private category for Ambassadors. As we have a group of over 100 volunteers and I'll have to add them manually already once to the second type of group, I wish I didn't have to repeat that process to add them to the private category.
Is there a way to avoid that process?
Also why are the two groups name similarly when they are two different things?