Frequently asked questions about iCloud Keychain – Apple Support
https://support.apple.com/en-us/HT204085
this describes how to change the security code
https://www.youtube.com/watch?v=z51h7DRkAeY
http://www.imore.com/forgot-your-icloud-keychain-security-code-heres-how-change-it but I can’t seem to do this…