Left Shoulder Level
 

I was told that while hitting, my left shoulder move down, and is not good. This is due to the preturn hip and the right arm pickup. And in Swinging the left shoulder will be more level.

Is this true that hitting will make the left shoulder down and swinging will be more level. Also even the left shoulder goes down is it bad?

Left Shoulder
 

The function of the shoulders is to turn around your spine. If your spine is bent forward (about 30 degrees) and tilted away from the target (about 15 degrees) that would suggest that your shoulders do make a downward motion.
If you are hitting, your focus should be pushing the club and your right forearm down plane and your focus should be on your right side because you can't push from the left side of your body. Focus on getting your right shoulder and forearm moving down plane, I think that will help.

Advice So Old It's New
 

"Get the right [side] in as I've told you, and the left side will cause you no trouble."

-- Tommy Armour
How To Play Your Best Golf All the Time (1953)