Hello Mohammad Ahmad fadelallah AlAzzam,
Thank you for posting in Microsoft Community forum.
Please check the password policy defined on domain controller.
Based on the description "the password can be changed by the domain admin but can't be changed by the user", you can compare the password changed by the domain admin, whether it is meet the password policy.
And you can compare the password changed by yourself, whether it is meet the password policy.
I hope the information above is helpful.
If you have any question or concern, please feel free to let us know.
Best Regards,
Daisy Zhou