There were two ways that I was taught to control trajectory.
First is with ball position, you are basically dealing with 3different ball positions. Front of stance, middle of stance and back of stance. Higher trajectory is front of stance, mid-trajectory is middle of stance and lower trajectory is back of stance.
Secondly, I was taught if you want to hit it high, you need to finish high. If you want to hit it low you need to finish low. A great way to visualize this is to picture a park bench in front of you. If you wanted to launch the ball over the bench you would finish on the high side. If you want to keep the ball under the bench you would have a much lower finish.
Both of these have been pretty consistent over the years.