For EB1A, there are 10(?) criteria that you only need

to fulfill 3 of them to qualify. So it doesn't matter much in what position did you apply.

Among those criteria, there is one which says that you are playing a critical role in your institution. If you used this criterion in your EB1A application, it becomes invalid if your new job doesn't match this condition. However, unless you get a interview for your 485, it is highly unlikely that they will use this to deny your 485 case. And in most cases, you should be able to find a similar job and should play sort of critical role in your new work place. Thus it is highly unlikely for USCIS to make a special investigation for your qualification.

All in all, your case might only be influenced if you used this special criteria. And even if you used it, I belive you are very very safe to quit your job and find a similar one.