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Can I change the Wallpaper shown on my Samsung Windows 8 Phone?
You can change your phone's lock screen background wallpaper.
From the Start screen, flick left to Apps list > Settings > lock screen. Tap the box under Background to select the lock screen background you would like your phone to use. With Windows® Phone 8, you can select from a photo, Bing® images (your background will change daily showing the Bing image for that day), select a background from a photo app like Live Wallpaper or Photo Editor.
When you select Live Wallpaper, you will need to set up the application. From the Start screen, flick left to Apps list > Live Wallpaper. Tap choose picture and select up to 12 photos to be used as a continuously changing background. Tap Done to save your selection. If you want to remove photos from the selected items, tap remove pictures.