How to Use and Edit Autofill for Forms in Firefox May 5, 2021, 10:24 am EDT | 2 min read Whether you choose to save addresses, payment methods, or both, you can speed up form entry using your web browser’s autofill settings. Here’s how to set up and use autofill in Mozilla Firefox. Enable Autofill in Firefox To use the autofill feature in Firefox, you must first enable it. And luckily, you can enable it for addresses and credit cards separately. This is convenient if you prefer not to use it for one or the other. To begin, open Firefox and click the Application Menu icon (three lines) on the top right. On Windows, pick “Options,” and on macOS, pick “Preferences.”