After an event is published, administrators can edit the details of the event. To do this, on the Events calendar, select the box with the date of the event. From there, click the title of the event to be taken to its individual event page.

On the individual event's page will be an Edit Event button beside the title of the event. Click on it to open the event's editing page.

The event's editing page allows you to edit any of the details of the event. You can click to the Basic Info, Participants, Location, Shifts, and Onboarding tabs, and change the information. Here, I have increased the number of shifts.

Once you've finished editing the event, be sure to go to the Review section and select Update.