Changing the System Theme Colour
1.
Press the Guide button.
2.
Scroll to System and press the A button.
3.
Scroll to Settings and press the A button.
4.
Scroll to Personalisation and press the A button.
5.
Scroll to Theme & motion and press the A button.
6.
Scroll to System theme and press the A button.
7.
Scroll to the desired theme and press the A button.