Turn on theUse Contact Infotoggle switch.
Your contact info is now enabled for AutoFill.
To change to a different contact, tapMy Infoand update it with the new contact.

Here’s how to change or update this information:
OpenContacts.
TapMy Cardat the top of the screen.
Your personal contact information is changed, and AutoFill will now pull this updated data.

Your phone number is automatically pulled from prefs.
you could add additional phone numbers, such as a home number.
key in your iPhone passcode or Touch ID if asked, or useFace IDif supported.

Add a credit or debit card manually or use the camera to take a picture of the card.
AutoFill can now access your updated credit card information.
TapEditand then tapDelete Credit Cardor change the credit card information.

To activate the iCloud Keychain:
Open theSettingsapp and tap yourApple ID/Apple Account bannerat the top of the screen.
Scroll down the list and selectKeychain.
Turn on theiCloud Keychaintoggle switch and type your Apple Account password if prompted.

UnderAllow Filling From, check that iCloud Keychain is checked.
FAQ
launch the Chrome app on your iPhone and tapMore>configs.
TapPayment methodsorAddresses and moreto view or change your options.

Toturn off Chrome Autofill tweaks, fire up the Chrome app, tapMore>tweaks.
TapPayment methodsand turn offSave and fill payment methods.Next, selectAddresses and moreand turn offSave and fill addresses.
In Firefox, go toMenu>Options>Privacy & Security.

You canmanage Firefox Autofill settingsin several ways, including disabling the parameters completely and manually adding contact information.