Hello Angela,
Thank you for positing your query on Microsoft Community forum.
When you set custom desktop wallpaper, it remains unsaved in the My themes section. After you change the wallpaper it automatically replaces the previous one with the new wallpaper which you have set. If you want to save the custom wallpaper, you will have to save it in My themes section from the personalization screen. Please refer the steps provided below for information on saving a theme.
- Open Personalization by clicking the
Start button
, and then clicking
Control Panel. In the search box, type
personalization, and then click Personalization. - Click your unsaved theme to apply it to the desktop.
- Click Save theme.
- Type a name for your theme, and then click Save.
For information on creating and saving a theme, please check the Microsoft help article provided below.
Hope this would help. If issue still persists post back with current status of your computer and result of proposed suggestion, we will be happy to assist you.
Thank you.