Step by step
Open Booking Details
On Calendar, click the booking so Booking Details opens in the side panel.
Choose Change employee
Under Actions, choose Change employee. The Change Employee dialog opens and shows the current employee and service.
Review availability
Each employee shows Available or Busy for that time. Prefer someone marked Available when you can.
Select and close
Select the employee who should take the booking, then Close when you are done. The calendar updates to the new staff column.