A county board which has adopted the resolution authorized in section 375.56 shall promptly appoint a personnel director or assign the function of personnel director to an existing officer or employee. In a county which is operating under an optional form pursuant to sections 375A.01 to 375A.13, the authority to appoint the personnel director shall be the same as for the appointment of other department heads. The terms and conditions of employment of the person appointed as director or assigned the function of director shall be established by the county board.