Up, Down, Up, Down
Changing direction used to be all about up-and-down motion. Skiers sank down at the end of a turn to maximize edge, then prepared to come up (1). That up-motion unweighted the skis for a split second, and let them flatten (2). This was a good time to pull the feet beneath the body, change edges and pivot the skis into the next turn by shifting weight to the new outside ski (3). At that point you had to begin edging again with the knees. The result was a sinking or down motion (4). All this up and down required a lot of work and made you feel like a yo-yo. Today's skis prefer even pressure and less pumping action.
Just Cross Over
New equipment and a widened stance let skiers change edges with less effort. Weight transfer happens earlier. In anticipation of the next turn, redistribute your weight onto what is going to be the new outside ski (A). Then, instead of rising up, you move sideways, across the skis toward the new turn. This crossover automatically changes the edges, and the effort of twisting the skis toward the fall line is eliminated (B). Instead, the pressured outside ski, which is on a high edge because it is so far out from under you, scribes a slicing arc (C). Ride that turning ski, and let your feet come back under you (D).