On a web browser, tap Edit Contact if you want to make any changes to that entry in your address book. You can make it so Gmail automatically saves the email addresses that you reply to in Settings > General > Create contacts for auto-complete. “[1] X Research source
Click or tap Done when you’re finished. [2] X Research source If that person is already a contact and you just want to add the new email address, tap Add to Existing Contact instead.
If you’re using a phone or tablet, tap the name instead.
Click or tap Save when you’re finishing editing. [3] X Trustworthy Source Microsoft Support Technical support and product information from Microsoft. Go to source