For Android phones, copy and paste this link http://www.xiaoyi.com/download/sports into the browser on your phone. After you click "Install Action Camera APP", click Ok. Click open to install the file. Allow your phone to install the app from another source. Go into the downloads app folder on the phone and open the sportscamera.apk file. Click Install, when asked to install this application.
For iPhones, you can download the YI Action app from the App Store. On your phone click on the link to be directed to the App Store.