BAD PASSWORD: is too simple

Because you might gave  3-4 characters only so its looks simple . always try to set with atleast 6-9 letters including uppercase and numeric number .

It doesnot mean that  password chnage didnt happened. It will change password successfully but not a secure .

[root@tstvm ~]# passwd sai
Changing password for user sai.
New password:
BAD PASSWORD: it is too short
BAD PASSWORD: is too simple
Retype new password:
passwd: all authentication tokens updated successfully.
[root@tstvm ~]#

BAD PASSWORD : it is too short