A guest wants to move their booking to Saturday. Can I edit it?

There is no edit button today. Cancel the old booking with the Cancel button on Orders → Reservations & waitlist, then add the new one with the Book form at the bottom: name, people, when, phone and a table if you want to give one. Both rows keep their history and say which way they arrived. Tell the guest yourself, because a booking made by hand sends them no message. The Tables, tabs and the kitchen screen tab in the docs covers bookings taken over the phone.