To make changes to a booking, simply click anywhere on the appointment to surface the modal. Click the "edit booking" button:
This will open the booking window where you can edit whatever you need
Edit the duration or price of a service
Simply click on the service you want to edit and a drop down will appear with some options.
Click the + to increase duration and - to decrease. To change price just click in the box, delete what's there, and type in your new price.
Remember to hit Save Changes!
Add another service
In the right hand booking window, simply click on the category of the service you want to add and click on the service to add, or search for the service and click to add:
The service you add will automatically go underneath the existing ones, but don't worry, you can just drag and drop them to where you want it:
You can even drop it on top of another service if you want to conserve space in the calendar:
Change a service
You might want to change your client's appointment from Balayage to Half Head Highlights.
In the booking window, simply click on the service you want to change, and then click "Remove":
Then select the new service you'd like to change it to and it will get added underneath the existing services, but don't worry, you can just drag it back up to where you want: