I spent some time to study the AC21 106(c). Based on my understanding, employer sponsored I140 has to notify CIS any change of jobs.
However, I am still comfused if I have to submit a notice because I am self-sponsored NIW.
The memorandum of 08/04/2003 says:
"It is expected that the alien will have submitted evidence to the office having urisdiction over the pending Form I-485 that the new offer of employment is in the same or similar occupational classification as the offer of employment for which the petition was filed."
However, to a self-sponsored case, there is no such a "offer of employment" at all.
Anyway, I found there are too many gray area in the law system. That's probably why lawyers can make money.