It may be a matter of borrowing power. I've been working out for a year, and it takes about 4 months to really start without help. Now every time I finish practicing my shoulders, I feel like a pump, and my shoulders become hard. My shoulder is uncomfortable. It takes time. My movements are standardized. Take your time, don't rush for success, and pay attention to the stimulation of the front, middle and back three parts. If it's too heavy, it's inevitable to borrow money. Novices can't control the main muscle groups well, which is likely to cause main muscle errors, that is, they haven't practiced at all. I suggest using a small weight to calculate the output first, and then consider the weight after finding the muscle feeling.

I hope I can help you!