The accounting officer is personally liable on his bond for the amount of any obligation incurred by his erroneous certification as to the sufficiency of an appropriation or of a cash balance, or for any warrant drawn when there is not a sufficient amount unencumbered in the appropriation or a sufficient unencumbered cash balance in the fund to pay the warrant, or for the payment of any amount not legally owed by the county. Any officer purchasing any supplies, materials or equipment is liable personally and on his bond for the amount of any obligation he incurs against the county without first securing the proper certificate from the accounting officer. The other officers, as the county commission requires, shall each give surety bond in an amount fixed by order of the county commission for the faithful performance of his duties and for a correct accounting for all moneys and other property in his custody. The sufficiency of the sureties shall be approved by the county commission. Any premium on the bonds shall be paid by the county.