How to exit the event to get back to settings
In the iOS app if you're in an event and you want to access the settings, exit the event by holding down two fingers on the screen for a few seconds.
By default you will be prompted for the same touch/face/passcode authentication that you use to unlock the iPad. You can set a custom passcode from the first page of the event settings, near the bottom.
Did you set a custom passcode & forget it?
You can find the exit-event passcode on the web-app, here: https://dashboard.booth.events/devices