Check your firmware on your 70d to be sure you have version 1.11 correctly installed just to be sure. If so, your settings should be saved. That is, if you had it set on high gain when you powered down, it should be on high gain when you power it up. Phantom power will always ask you to confirm it when you power on. But your other settings should be there.
Otherwise, you may need to be thinking about a warranty claim.
that's my personal opinion.