How to turn off Apple Intelligence on all your Apple devices

With the latest versions of its software--specifically iOS 18.3, iPadOS 18.3, and macOS Sequoia 15.3--Apple has now turned on Apple Intelligence by default. That means all of the associated AI tools will be ready and waiting to help you as soon as you've installed the updates and restarted your device. However, Apple isn't (yet) forcing you to use all of these features, and you can still turn off Apple Intelligence, if you'd like to. Note that if you've previously turned Apple Intelligence off on your device, the iOS 18.3, iPadOS 18.3, and macOS Sequoia 15.3 updates won't suddenly turn it back on--your previous choice will be respected. If you're new to Apple Intelligence and want to know what you're dealing with, it's a suite of AI features covering just about every app on your phone.