New User

Check if you accidentally have caps lock on, or maybe had it on when the password was chosen.

If you still can’t login, then login to your other admin account, go to System Preferences->Users and Groups, click padlock, authenticate, then select the new account and click Reset Password

Let me see: this account, let's call it wife, can't login, and you can login to your account, but trying to reset the password for wife, from your account, fails. Is that it?

I don't understand the last part:

. Hit ? It excepted new hint. I even reinstalled system - the same.

Were you able to change the hint, but not the password?

Please run Etrecheck and post its full report here. Use the "additional text" button and paste the report into the text box.

Was the New User Account created from an Admin. Account ?