Press and hold on any open space on the home screen, select WALLPAPERS, select PHOTOS, scroll through and select the photo you would like to set as your screensaver.  Then select WALLPAPER in the upper left hand of the screen.  Use this video to learn how to do this on the XP8:

 

 

If you need any further assistance with this question, please contact the Sonim Customer Experience Center at 1-833-MY-SONIM (1-833-697-6646) or email us at [email protected]  We are open 24 hours a day, Monday-Friday and we will further assist in troubleshooting.