There are two places where you can control which guest see certain content.
In the Guest List located in the drop-down menu below your name in the upper right side, you will see three columns next to each guest's name. Here is where you choose to make a guest a Care Coordinator, let them read your updates or allow them to leave a comment or message. The default for reading updates and leaving comments or message is "yes". To change the setting click "No" under that specific column. When you are finished making your changes, click Update. Now your changes are saved.
In the Helping Calendar, you can select who is NOT allowed to sign up for a specific type of event (i.e. transportation). In the Helping Calendar tab. click on Guest Permissions. You will see a column at the top fo reach type of event. If you don't want a guest to sign up for any transportation events, then uncheck that box next to their name. A red dash will appear which indicates they cannot sign up for that specific event type. The guest will see the event on the page and it will appear to them as no more volunteers needed (green check mark).