Old Testament and New Testament Sabbath 2 (1)

Since the priesthood changed from the order of Aaron to the orderof Melchizedek, what else changed? 

In Hebrews 7:12, it reads, For when there is a change of the priesthood, there must also be a change of the law.

 As we can see, something changed not abolished. When we can think about the word "order" as in the order of Melchizedek, what does it signify? Basically, the way or manner it which something was kept from the Old Testament to the New Testament. In order to understand the change, we need to understand how it changed from the Old Testamentto the New Testament. Then, in order to understand how Sabbath is kept in accordance with the example that Jesus Christ taught us, we need to understand how it was kept in the Old Testament.