Perhaps you’re thinking of the Aaronic Priesthood, which is conveyed on practically every little LDS boy.
The Melchizedek priesthood is bestowed on only the “important” men in the church? Yes, I was mistaken. Pardon my ignorance if I’m wrong but wasn’t the last Priest of the Melchizedek Priesthood, Jesus Himself, the last and still “King of Salem”? What is their reasoning concerning their pretended authority to do that?
For that matter, how do they reason, to bestow the Aaronic priesthood on anybody, that office belonging to Aaron and his descendents, all by birth and all of the tribe of Levi?