how do I reset my iCloud security code?

On a computer, System Preferences/iCloud, Keychain/Options and change the number there.

On your device, go to Settings → Your Name → iCloud → Keychain and switch Keychain off then on again.

Tap "Approve with Security Code", tap "Forgot Code" and then tap "Reset".

Follow the instructions to reset iCloud keychain and create a new passcode.

For Problems With Your Apple ID

1. Forgot iCloud Password
2. Forgot Apple ID
3. iForgot Password - Apple ID
4. iForgot UserName - Apple ID
5. Apple ID - Apple Support
6. Manage your Apple ID primary, rescue, alternate, and notification email addresses
7. About your Apple ID email addresses
8. Get help with Apple ID
9. Contact Apple for help with Apple ID account security - Apple Support
10. What to do after you change your Apple ID email address or password - Apple Support

Reset Security Questions

Contact Apple for help with Apple ID account security

You may need to reach Apple’s Account Security department. If you cannot find your country or are not able to call, then complete this form and send it to them.