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It's the {"smallUrl":"https:\/\/www.wikihow.com\/images\/7\/7e\/Iphonesettingsappicon.png","bigUrl":"\/images\/thumb\/7\/7e\/Iphonesettingsappicon.png\/30px-Iphonesettingsappicon.png","smallWidth":460,"smallHeight":460,"bigWidth":"30","bigHeight":"30","licensing":"<div class="mw-parser-output"><p>I edited this screenshot of an iPhone icon.
<\/p><p>License: <a rel="nofollow" class="external text" href="http:\/\/en.wikipedia.org\/wiki\/Fair_use">Fair Use<\/a><br>
<\/p><\/div>"} icon typically found on the home screen. It's at the bottom of the third group of settings. It's at the top of the list. If the switch was already on/green, there's no need to toggle the switch. It's at the bottom of the list. If the switch was already set to the On position, your iPhone or iPad is already set to calibrate automatically. If you don't see this option (this could be the case on older phones and tablets), skip to the next step. It's a black icon with a white compass and red arrow inside, typically found on the home screen. If you were able to calibrate the compass using the previous steps, you should now see your current direction, and there's no need to continue with this method. However, if the compass must be calibrated manually, the "Calibrate" screen will appear, along with some on-screen instructions. Follow the on-screen instructions to rotate your phone or tablet so that the ball makes its way around the circle. Once the ball reaches its starting point, the compass will be calibrated.

Summary:
Open your iPhone or iPad's Settings. Scroll down and tap Privacy. Tap Location services. Slide the "Location Services" switch to On . Scroll down and tap System Services. Slide the "Compass Calibration" switch to On . Open the Compass app. Tilt the screen to move the red ball around the circle.