The skis should be so the wide side is under the sled, that makes the stance narrower so you can sidehill easier, but there is still adequate surface area in the skis to keep you up on the snow.
Are you turning in the powder or on the trails? Turning in the powder involves learning a technique called countersteering. Take a watch at this video, it demonstrates how to do it pretty well.
https://www.youtube.com/watch?v=f3wZRciVTmQ