By default, the guest can go back to his registration form at any time and modify his answers. However, the organizer may decide to prevent any modification of the guest's answer to a question depending on his status at the event.

To do this, when you add a field to the form, you must click on the 'Advanced' button of the question and then tick the box 'Do not allow the guest to modify this if his/her status for the global event is:' and tick the desired status.