Changing Log in name

I am using the free Adobe Acrobat Reader DC, version 2018.011.20038 on a MacBook Air.

I want to change my name permanently in the comments section. I have already looked this up in other forums but haven't yet found an answer that works. I am a teacher and cannot present myself as one name and have my comments display another.

Here is what I have already tried:

1) In Preferences, on the "commenting" tab, I have already clicked on AND off the "Always use the Log-In Name for Author Name" - neither "on" or "off" changes my name. This is due to #2 below....

2) In Preferences, on the "identity" tab, I cannot change the log-in name (which is my former name). It does not permit changes. My "name" in the next filed is correct though. It is the LOG-IN name that won't change. I went to my online account, but that's okay, has the correct name, so I don't know why my "log-in name" in my app is wrong.

3) I tried Right-clicking my name in the comments section and going to Properties > General > Changing the author > making it the default. But that only changes one comment name at a time, and DOES NOT alter future comments (even though I clicked on "make it the default name".)

I am thoroughly baffled now. What else can I do??