The Council shall fix the salary of the Auditor, which salary for the calendar years 1972 through 1975, shall be fixed, prior to January 1, 1971, by the Council holding office on the date of the adoption of this Charter.
   If the established salary of the Auditor is to be changed or adjusted in respect to a succeeding term of office, such change or adjustment must be made by Council not later than January first of the last year of the elective term then being served by the Auditor, but the salary shall not be increased or decreased so as to be effective during the elective term of office which is then being served by the Auditor. Unless, and until the salary is changed, it shall remain as last fixed.