Question: how do you change your background on samsung?
Answer: 1 Open the Gallery.
2 Select the picture you wish to set as wallpaper.
3 Tap the options icon in the top right corner of the screen. ... 
4 Tap Set as wallpaper.
5 Choose whether you want to set your wallpaper to your Home screen, Lock screen or your Home and Lock screens.
6 You can now adjust how the wallpaper will look.