The setup is horrible and nearly unusable.
The spring tension in the arm is so strong you need 3 men and a boy to tighten the knob so the arm you shorten stays shorter than the other one.
Assuming you can tighten it that much, then comes the problem of getting it loose again so you can close the awning.
You don't even want to know what happens if you close the electric awning with one arm shorter than the other.