Android Lollipop introduces a number of new features and improvements that can be difficult to manage. One of the most important aspects of managing an Android device is locking apps. Locking apps prevents unauthorized access to your device and can help protect your data. To lock an app, you first need to find it in the list of applications on your device. To do this, open the Settings app and select Security. Then, under App Protection, select Lock apps. You will now see a list of all the apps on your device that are locked. To lock an app, simply click on its name and then press the lock button.