The Board shall appoint a secretary and a treasurer, who need not be members of the Board, to hold office during the pleasure of the Board, and fix their duties and compensation. Before entering upon the duties of their respective offices they shall take and subscribe the constitutional oath of office, and the treasurer shall execute a bond with corporate sureties to be approved by the Board. The bond shall be payable to the District in whatever penal sum may be directed by the Board conditioned upon the faithful performance of the duties of the office and the payment of all money received by him according to law and the orders of the Board. The Board may, at any time, require a new bond from the treasurer in such penal sum as may then be determined by the Board. The obligation of the sureties shall not extend to any loss sustained by the insolvency, failure or closing of any savings and loan association or national or State bank wherein the treasurer has deposited funds if the bank or savings and loan association has been approved by the Board as a depositary for these funds. The oaths of office and the treasurer’s bond shall be filed in the principal office of the District.