Dbowner For The Model Database

How do I change the Database owner for a MODEL database?
When I open the properties for a Model database, it shows "UNKNOWN" as the database owner, and I can't run the command 'sp_changedbowner 'sa' as it's not allowed to run on master, model, and tempdb.
Any help?why would you want to, it's used as the template for future databases created on the server.|||Because I cannot run the sp_helpdb command.