When a user saves an event to their calendar, the event contains the event details as they were in AddEvent at the point in time when the event was added to their calendar. This means that if you later change or update the event details, these changes will not be reflected in the calendars of users who have already saved your event to their calendars. If you have already shared an event with your users and you need to edit or update the event details, you will need to share the new or updated event with your users again. You should also ask them to remove the previous event from their calendars to avoid confusion.
If you know ahead of time that you will need to update an event’s details after it has been shared, you should use an add-to-calendar button for a subscription calendar instead of an add-to-calendar button for an event. Sharing a subscription calendar with your users creates a dynamic link between your users' calendars and AddEvent, which means that any changes to your AddEvent calendar will be reflected in your users' calendars. This also means that you can share multiple events at once, rather than a single event at a time.