Every U. C. D. policy shall contain a provision relative to statements in the applications and changes in the policy which shall be in one of the forms set forth in (a) and (b) hereof at the option of the insurer (or in the substance thereof):
"No agent has authority to change this policy or to waive any of its provisions. No change in this policy shall be valid unless approved by an executive officer of the insurer and such approval be enclosed hereon.
"No agent has authority to change this policy or to waive any of its provisions. No change in this policy shall be valid unless approved by an executive officer of the insurer and evidenced by endorsement hereon, or by amendment hereto signed by the employer and by an executive officer of the insurer."
Cal. Code Regs. Tit. 10, § 2244.3