Open the Settings app on your device to begin adjusting your privacy settings.
Tap on Privacy in the settings menu, then select Groups to manage group settings.
Choose the Everyone option, allowing anyone, including non-contacts, to add you to groups.
Select My Contacts if you want only contacts in your address book to add you.
Choose My Contacts Except... to exclude specific contacts from adding you to groups.
If excluded contacts try to add you, they must send a private group invite instead.
Tap Video Off if prompted, to disable video in the group settings.