While you can configure working hours for each staff member from the Staff section, you may want to customise this further and have different working hours on specific days. This can be done through staff scheduling.
To configure staff scheduling, click on My Business and then on Hours and Scheduling:
Under the Staff Scheduling header, click on 'Edit':
From this screen, you can browse forward and backwards to different dates and see the staff working hours in green. You can either drag the green section to move the shift earlier or later or drag the start or end time:
Doing this updates the working hours in the appointment calendar immediately. If a staff member is not working on a specific day, you can either create a Close Out from the appointment calendar or click on the green bar from this screen to create the closeout: