Whenever you do not use the Sony Xperia Z3 Compact for a certain time period then it switches automatically into the standby-mode. The standby can also be activated by briefly pressing the Power On / Off button. In stand-by, the so-called lock screen is displayed then the smartphone is reactivated. On this lockscreen informations such as time, weather, etc. are displayed. In the background a lock screen image is always displayed. This wallpaper of the lock screen, can ba changed in Android. To change the background of the lock screen of your Sony Xperia Z3 Compact proceed as follows:
Tap at the Home Screen on the menu button, which takes you to the apps. Here you can see the icon for "settings". Navigate from here to "Personalization" --> "Screen lock". Select one of the options and then follow the instructions to change the background. You can choose between pre-installed images or your own. You now know how you can change the wallpaper of the lock screen on the Sony Xperia Z3 Compact.