iOS 4 is easy to use, but it’s also packed with features. That means the Settings app gets pretty complex—so complex that you’re bound to miss out on some terrific options. That’s why we’re highlighting four of our favorites that tend to go undiscovered. For starters, triple-tapping the Home button (toggle the triple tap on and off in Settings > General > Accessibility) can invoke accessibility settings—including our favorite, White on Black, which reverses colors on your iPhone screen. Aside from freaking out your friends, it’s great for low-vision users or anyone squinting at an iPhone screen in bright sunlight.