Drag a booking on your calendar to a new time or day, and tell the client.
On the Schedule week view, drag the booking to its new time or day. It snaps to 15-minute steps, and a dashed outline shows where it will land.
Check the From and To times in the dialog. Change the date or time there if you need to.
If the new time overlaps another booking, you'll see a warning. If concurrent bookings are off in your settings, pick another time.
On a team, choose whether to keep the assigned person or reassign the booking. The list shows who is free.
Leave Notify ticked to tell the client the new time, or untick it if you've already told them.
Click Move. Cancel leaves the booking where it was.
The booking moves, and reminders use the new time. A draft invoice updates to match, unless you've changed its price by hand. An invoice you've already sent or that's been paid stays as it is, so update it yourself if the amount or date needs to change.