Human: How do I change my iCloud security code verification number on an iPhone? Assistant: 
Change Your iCloud Security Code Verification Number on an iPhone
1. Open Settings.
2. Tap iCloud, then tap your Apple ID.
3. Tap Password & Security.
4. Tap Add a Trusted Phone Number.
5. Enter new phone number and tap Send.
6. Enter verification code.
7. Tap old phone number.
8. Tap Remove Phone Number, then tap Remove.