EB2 green card keep priority date for job change after i140 approval

[skypemesm]

Hi, My employer had currently applied for my I-140. If I change my job after the I-140 approval, will I be able to keep the same priority date, or will it be a totally new application? Will it depend on the goodwill of my current employer? My job description will be still be in software development (as now), although in a different domain. Please let me know. Thanks.