The Purchases/Registration element is a combined element used for guests to register and/or purchase tickets/items or make donations.
The default webpage template contains either Registration and/or Purchase pages depending on the one you chose. If you are selling tickets online, this will be a Purchases page, whereas online registration without a purchase is typically configured on a Registration page. Each of these pages contains a Purchases/Registration element.
Open the webpage that has the element you want to configure.
If you have a Register page, and are already registered as a bidder, then the menu link will be hidden. In this case, hover the mouse pointer over the page editor icon (three cogs on the left) and click on the Register page in the page list.
The element will indicate if you are already registered but you can still access its Settings option.
To access the Settings, hover the mouse pointer over the element and click the Settings editor link.