Sat Nav volume

Can't seem to find the volume control on the sat nav ...anybody help?
It's probably obvious but can't seem to find it

I found it by accident today! When she speaks an instruction, turn the volume up.

Thanks Rhys will give it a try. Will she then remain at that volume or revert back to her quiet voice?

Change it in menu on the touchscreen,there are all the presets on there for phone. sat nav etc.