The way I turn off the motors for my Phantom 2 is by only holding the left stick down when its on the ground...
Could i accidentally turn off the motors if I am in the air holding the left stick down while descending?
There's a firmware parameter in the 'Advanced' section of the 'View' tab labeled: Cut Off Type:, this should be set to "Intelligent".
There's also an "Immediate" option which you don't want and may result in mid-air shut-down.
You'll have to work through the translation but you can learn more here: