1. Open the main interface of Peace Elite and click Warehouse.
2. The warehouse option pops up on the right side of the page, and click Combat Readiness.
3. Enter the combat readiness options interface and click the picture icon.
4. Click the picture icon, and two pictures will pop up on the page. Click another background picture.
5. After selecting the cool flat wallpaper, click the cross in the upper right corner of the page.
6. Return to the main interface of the game, and the wallpaper will be replaced with cool flat wallpaper.