If you have set a service to Booking Option 2 or 3, where the client can book without choosing a Service Provider, those appointments will appear in your company calendar as yellow in color and with the notation “TBA”.  In the Day view, you can drag & drop the appointment to the appropriate service provider, or in the Week view, select the booking to assign a Service Provider.  Once assigned, the booking will display in the service or service provider color as defined in the Settings / Configurstion / Advanced / Company Settings. 

Also, on the top right of the calendar, if there are any TBA appointments, the wording “TBA Appointments” will be flashing.  Select the indicator to access the list of TBA appointments.  Select an appointment in the list to be taken to that day in the calendar to assign the booking.