Guest Permissions allow you to manage which guests can sign up for a specific category of events (for instance, there are only 2 guests who you want to ride with to your doctor's appointments).
Deselect the check mark under the doctor's apt column for the guests NOT allowed to volunteer for doctor appointments. Then click Save Changes. A red dash will appear instead of the green check mark.
The default is that all guests can sign up for all event categories.
If you have a question, contact firstname.lastname@example.org.