how to change service name in app_confirmation in appointment plugin?

need to change "service name" and "service provider" inside the app_confirmation. I've been at this for hrs and cannot figure it out. There is no short code for this as i know of. Yes i did check the short code list. and it is the confirmation app when trying to set an appointment.

so I want "service" to be name "subject" instead of "service". you can view the image.