Hi Naheed, You can change background,refer to the below forum links for background color: https://support.mozilla.org/en-US/questions/1020987 for background image: https://support.mozilla.org/en-US/questions/1271362 new tab wallpaper: https://support.mozilla.org/en-US/questions/1183452 use the articles for customization according to your preference if anything doesn't work mention article link I given and reply back