The board may at any time increase, reduce or discontinue any revolving fund established by its order. If the revolving fund is ordered reduced, the officer using it shall immediately return to the county treasurer the amount necessary to reduce the fund as ordered by the board. If the fund is discontinued, the officer shall immediately refund it to the county treasurer. A reasonable time shall be allowed the officer to reimburse himself by demand on the county for expenditures legally made from the fund. If the revolving fund is ordered increased, the officer entrusted with the fund shall comply with the provisions of this article relative to the amount of the fund as increased by the board.