Auto-Fill not working with Windows desktop app

In the browser extension configuration, it's the last topic of the top "General" section, just above the "Security" Section.

Autofill in one go only works with the browser extension, as far as I know. The desktop app will not paste 2 fields at once. Usually, you don't need this. If the browser extension is working properly, it will seamlessly offer autofilling, as soon as you surf to any website for which you have some login in 1Password. Because of this, you don't need to use 1Password like a website favorite list. Don't search for an item in the 1Password desktop app. Instead, you just use your browser favorites in the browser. If a login dialog appears, and there is an item for that website within 1Password, you will notice 1Password will offer the corresponding credentials. You don't search explicitly, 1Password searched this for you in the background.