For the most part, you will want to hold a single spot at a time but when needed you can quickly hold all open spots.
To Hold Open Spots:
Navigate to the class where you want to hold all spots. Click the three vertical dots in the top right corner and click Hold All Spots. All empty spots will now be held and unable to be reserved by customers.
To Release All Holds
From the class roster page, click the ellipsis menu on the left side and click Release All Spots. All empty spots will now be available for customers to book.
