Due to some security issues with CPanel and postgres, final users can't change Postgres charset when creating a new database.
If you want a database with a specific charset, go to your account and open a ticket requesting the creation of a new database. Tell the database name and the charset. The charset must exist at the postgres documentation.
Also Postgres doesn't allow to change the charset of an existing database. You need to backup, drop your database and request the creation using the steps above.