[With regard to any county that is exempt from the provisions of Section 19-2-3, this section shall read as follows:]
The board of supervisors of any county is authorized, in its discretion, to employ a county administrator. The person employed as county administrator shall hold at least a bachelor's degree from an accredited college or university and shall have knowledgeable experience in any of the following fields: work projection, budget planning, accounting, purchasing, cost control, personnel management and road construction procedures. Such administrator, under the policies determined by the board of supervisors and subject to said board's general supervision and control, shall administer all county affairs falling under the control of the board and carry out the general policies of the board in conformity with the estimates of expenditures fixed in the annual budget as finally adopted by the board or as thereafter revised by appropriate action of the board.