Not only are we one foot dominant, our front foot when riding regular, but that entire side of our body is dominant.
When learning to ride switch, I found it really helps to think of keeping your shoulders in line with your board. That forces your dominant side to stay at the "back of the bus" over the back of your board, where it belongs.
When learning switch your dominant side will still want to "lead" and that is completely counter productive. You goal is to learn to be comfortable with either side of your body being the "boss".