How my Apple ID password changed

Are you asking how to change your password or did your password change, but you didn't change it?

if you know the current password.

 Apple ID Password Change.   -   

 What to do after you change your Apple ID or password - Apple Support  -   I suggest doing this before you change your Apple ID or password.

If you forgot the Apple ID (iCloud) password or someone else changed it, enter the Apple (iCloud) ID, and click Forgot Password. See if you can get a Rescue or Notification email option if necessary. Link to contact Apple Support at the end of the 2nd article.

Apple ID - Manage  -     

Apple ID – Forgot Password  *