A theme is a unique combination of colors, icon shape, font, and wallpaper. Apply themes to easily change the entire appearance of your phone. You can choose from existing themes or create your own.
You can change individual settings for your phone's appearance, which layer on top of your selected theme.
To create your own theme:

If you like the way your wallpaper, font, color, and icon shape look together, create a new theme for the combination instead of changing the individual settings. That way, you can easily go back to the combination later.
You can change these Personalize settings:


Quickly change the default sounds for calls, notifications, and alarms.
Set lights to flash (or not flash) when you receive incoming calls and notifications, and when alarms sound. Learn more.