If AutoFill won’t work
Safari can automatically fill in forms, user names, and passwords for you. If this feature isn’t working, here are some things to try.
Make sure AutoFill is turned on
Choose Action menu > Preferences and click AutoFill. (The Action menu is near the upper-right corner of the Safari window, and looks like a gear.)
Select “Using info from my Address Book card” and “Other forms.”
Check the webpage for forms
The webpage may not have any fields for AutoFill to complete.
If AutoFill still doesn’t work, Safari may not be able to match any of your personal information to the fields in the webpage form. For instance, Safari uses the information on your address book card to fill in forms. If a form requires your phone number but the number isn’t on your card, you’ll have to fill it in manually.