You add the practitioners default charges by clicking on the 'Settings' section within their record.
This will then bring up the practitioner's locations. As you can see, Molly Morrison is active in 3 different locations and has chosen to use different charges at different locations.
To edit a charge, click on 'Change' beside the charge you wish to make changes to.
A drop down will then appear with all of the available charges to chose from. Simply select the charge you wish to associate with that appointment type and location.