Wow where do you begin with bad advice keep your head down stay still make good contact. By far the worst advice that I have seen over 40 years is to keep your left arm straight.(right arm for leftys) It’s only half true. We are trying to swing the golf club and the clubhead in a circle around us. So our backswing and our forward swing Should be symmetrical. That means that our right arm for a right handed player should fold on the backswing And our left arm should fold on our follow through. If you hold the club parallel to the ground and you keep it parallel to the ground on your backswing and your follow through you will feel how your elbows work in the swing. For anyone that is a beginner or does not break 80 learning to use your elbows correctly and to not keep your lead arm Straight ( right arm for a lefty)
Is the secret to golf. There is no straight in golf The clubhead swings in a circle around us.