Ok... I know why the problem exists now...
I've been using basically version 12286 (Jan 1, 2021)... and testing out newly night builds when they coming out...
So, basically, when switching between 12286 and any version from 12596 (Dec 20, 2021) onward, the keybinder20.conf will reset to initial default... But, switching from 12596 (Dec 20, 2021) onward and later versions after, the conf file will not be reset...
Why do I still use the old version 12286? Because, for my computer, all later versions will crash intermittently after saving all files or creating a new class, and I don't know why it only happens to me (obviously, since no one else reported). Right now, I am still trying out the latest version 12672...