If a commission is created, the terms of office of the three commissioners first appointed shall be one, three, and five years, respectively. Thereafter, original appointments shall be for a five-year term. If a commissioner is appointed, the first appointment and any subsequent original appointment shall be for a three-year term. In case of a vacancy in the office of a member of the commission or in the office of the commissioner, the governing body shall fill the vacancy by appointment for the balance of the term. The city auditor shall be ex officio clerk of the commission or commissioner.