There are arguably four positions. I say arguably because I am not a fan of positions because they can be misleading. If these positions come from momentum, you are doing fine.
How do you get your arms to straighten naturally, without effort? Watch Part 2 to strengthen your understanding of Impact.
Once you have your elbow working correctly, add a shoulder lift. This is the second part to building a solid shoulder rotation.
When you understand how the body is designed to move, proper shoulder rotation becomes easy. This is why and how we hinge the wrist.