Hi Kay! Keep your arms in the "oak tree" position....meaning that you imagine your arms wrapped around the oak tree and this amount of curve in each arm never changes. Your arms will lower to the side and raise to the top but the actual amount of bend/curve in each arm will remain the same no matter what point of the exercise you are in. See if this helps!
Awareness tip:
Many people don't realize that they open their angle even wider at the bottom of the movement and this stresses the shoulder and elbow joint.