If you want to change the nickname of a database, or if you want to change the priority of your databases, use PROUTIL with the 2PHASE MODIFY qualifier:
When you specify -crd, PROUTIL toggles whether or not the database can serve as a coordinator database. If you specify -crd against a database that is a candidate for coordinator database, it is no longer a candidate. If you specify -crd against a database that is not a candidate, it becomes a candidate.
When you specify -tp nickname, PROUTIL identifies a new nickname for the coordinator database.