How do I get my disability award changed?

I would apply for an increase with your CVSO. If you are already service connected you need to be aware they can also lower your rate. Go to your CVSO they can help you determine what is the best for you. Based on what your stating above I would look at the 38CFR and see if you meet the next level rating. https://www.govregs.com/regulations/expand/title38_chapterI_part4_subpartB_subjgrp102_section4.71a

But most importantly go see your County Veteran Service Officer

You file through ebenefits for an increase of your already service contact shoulder. But make your you have continuity of care. Meaning you have been seen by either a private doctor or VA Dr. about the shoulder pain for all these years. Also know this, 10% is the rating for just painful Motion. In order to get higher you must have a substantial range of motion limitation.

You can submit a claim for re-evaluation. If you are not familiar with the process I recommend using a form of advocate who does this type of thing.