A question on changing job while 485 pending

I had a degree in Computer Science and I work for a hospital as a system analyst. In order to facilitate my NIW approval, I stated my research focusing on health informatics. The hospital sponsored my EB3-H1B. My current job was categorized into Programmer for EB3-H1B. My NIW 140 was approved but EB3-140 was still pending. Both NIW and EB3 485 have been pending over 180 days(since the last July).

How to define the same or similar jobs? Can I take a computer related job from a different industry, like a system administrator or developer in oil or pharmaceutical companies? If I change my job, will I lose my priority date on my EB3?

Thank you very much,