Toyota Crown 2004 Royal Saloon

[Aviation Investigation]

There are controls in the rear seat armrest for operating the audio system and rear shade. I can't get any of these controls to operate, yet the shade control operates at the front switch. 

Does anyone know if there is some control for the driver to be able to isolate these switches? [Similar to the electric window lock driver's switch.] I'm guessing that this might be why they're not operating. I've only had the car a few months. They've never operated from the time I bought it. I've an English manual but it isn't helpful. 

Any assistance would be gratefully received. 

Thanks. Declan. New Zealand