You can change the look and feel of your Firefox Preview app at any time. You can select from any of the pre-installed themes.
To change the Firefox Preview theme:
Tap the menu button.
- Tap .
- Tap from the Basics section.
- Tap one of the following radio buttons:
- Set by Battery Saver
If you select Set by Battery Saver, your Firefox Preview UI will be dark when the Battery Saving mode on your device is enabled.