To control phantom power, you need to hold down the tone key and then press the HDD and MENU keys.
The LEDS on the left side will indicate status of phantom power. You'll see them toggle as you press the left side control keys.
The switch above the XLR does not control phantom. The 722 will supply phantom to line level inputs for situations where a mic has a hot enough signal that the mic preamps need to be out of circuit.