How do I sign in on an old phone if I forgot my password?
How do I sign in on an old phone if I forgot my password (but still signed in on new phone, iMac, iPad, etc.)?
iPhone 4s, iOS 9
If you forgot the Apple ID (iCloud) password, 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.