You can change it in the mobile phone photo album. The method is as follows: 1. Step 1: Turn on the phone and find the photo gallery application. Figure 2. Open your gallery and go to the home page of your photo album. Figure 3. Select your album and go to the album image display page. Figure 4. Select a picture, click a few buttons below the picture, and then open the pop-up settings. 5. Select Set to, and then select the wallpaper option. Figure 6. Enter the wallpaper settings page and click the check mark button in the upper right corner. Figure 7. Click Set Lock Screen, and then set the lock screen wallpaper to finish.