How to solve error 15128 in Microsoft Sql Server ?
But first I want to explain which is the scenario. You are logged with Windows Authentication and you created a new sql login. Now you want to disable Enforce Password Policy. When you want to do that it Sql tells you that you can not save the user, a new password must be set. Strange...so:
- double click on new login created, leave the check boxes checked(enforce password policy and enforce password expiration) and change user's password temporally to what ever you want, click OK
 - then reopen and uncheck enforce password policy, enforce password expiration; Press OK
 - finally you reopen the user and specify the password you want
 - Test it ;)
 
Hope this will help you.