In the search head i tried to change the password of a user using below command, i got the success xml response but with the new password i am not able to login.
curl -k -u admin:temp https://localhost:8089/servicesNS/nobody/search/storage/passwords/user1 -d password=pwd_temp
Just did that:
curl -k -u admin:changeme https://localhost:8089/services/authentication/users/admin -d password=changeme123
and it worked like a charm check the URL you used, looks different to mine...