Changing the theme changes how your app appears. The theme doesn’t affect the layout and content. Different themes have different color sets.
To change the app theme colors,
1. Open PDF Reader Pro;
2. Click More in the upper left corner;
3. Choose Settings ;
4. Tap Theme Color;
5. Select a theme, tap Use, then click the back arrow to have it applied.
Note: It now supports multiple colors, including White, Red, Orange, Green, Cyan, Blue, Purple, and Black. And you can change the background theme colors while reading your PDFs with PDF Reader Pro.