Job change in same company (approved I-140)

[Bharath Kumar Alapati]

I have joined my current company 6 years ago in X role. In X role my employer filed for green card application. My i-140 approved in sometime 2014. In 2016 August i applied for promotion and i was offered that promotion (Role Y). My attorney mentioned that they have to start the GC process all over again in new role Y. But now i have a family situation where i want to work from home. My employer mentioned that i have to step down into my old role X in order to work from home.

Now my questions are:

•  Can i use my old approved I-140 if i go back to my old role X? 
• If my new address(work from home) is different from the old address that was used for PERM filing do I have to start the entire PERM process again?

I am confused.