Appointment of officers and employees; salaries and bond. All officers and employees of the county of Cook, in the classification hereinafter provided for, except those whose election or appointment is otherwise provided for by law, and except those enumerated in Section 3-14022, shall be appointed by the president of the board, according to the provisions of this Section. The salaries or rate of compensation of all officers and employees of said county, when not otherwise provided by law, shall be fixed by the board of commissioners and shall be fixed prior to the adoption of the annual appropriation, and shall not be changed during the year for which the appropriation is made. The board of commissioners shall also determine whether any or what amount of bond any officer or employee shall give.