The judges are appointed.
Even though they were apparently suggested by the assemblies of the people, they were appointed by Mosiah. Thus the kin-leaders received official public recognition by the king for their new positions. The hierarchy of judges is established by the selection of Alma the Younger as the chief judge of the land.
Alma the Younger now has two positions. He has become the high priest, or the head of the various churches. This position he receives from his father. He is also the chief judge, a position confirmed by Mosiah.
It is curious that the defacto separation of the religious from the political with Mosiah and Alma the Elder should be reunited in the person of Alma’s son. Nevertheless, even though they are reunited in one person, they are not reunited in function. The people would understand that Alma wore two official titles. This will become most apparent later when Alma relinquishes one of them. That will not be possible unless they are still considered separable.