How do I change the date, time or venue?

Open Design → Basics and edit the date, time or place. Press the date to pick another day from the month, and check the time zone beside the date as well as the time. A new event starts in your account's time zone, under Time zone in Account → Settings (the account control at the top of the page, then Settings on the Account page; Account → Your details in the app); changing it there changes only the events you make afterwards. Picking a zone beside an event's date sets it too, as the line under the choices says.

When you move the start, the end moves with it, keeping the same length, and so do two things set from the start: the time later guests arrive, when Some guests join later is on, and an RSVP deadline set to The day before or The week before. A deadline with its own date and time stays where it is. A closing time you set for nametags moves with the start too, keeping its distance from the event, and so does a time you set for Awards voting to open. The Design room says where the moved times now land, and the Overview says when later guests now arrive until you dismiss it. If the move would bring later guests after the event ends, it is refused until you change when they arrive, and so is an end that would come before they arrive.

An event has no end time until you add one with + End time: choose 2 or 3 hours, or Custom for a time of your own. An end time earlier than the start is the next morning, and the end's day then shows beside Ends, where you can press it to move the end to another day.

What guests should wear is one of the suggested sections in Design → Details, called What to wear.

Review the guest page after saving. If people have already been invited, send a message from Manage → Messaging explaining the change.

Do not assume an earlier email or a calendar entry a guest already saved will update itself. Include the new details and ask guests to check their calendars.