See also:

Call volume
Adjusting the incoming or outgoing call volume may improve clarity if reception between callers is unclear. - Incoming calladjusting this setting allows you to hear a difference in volume. - ...

Specifications. Wheels and tires
WHEELS AND TIRES ...

Steering wheel switch for audio control (if so equipped)
Steering wheel switch for audio control (if so equipped) 1. Tuning switch 2. VOLUME control switch 3. SOURCE select switch ...