All the platforms should use the Arcade - Marquee folder. Just place your images there and they need to be named as each game is named. After you add new images make sure you go to settings in BigBox and refresh the image cache. Other than making sure you have the monitors defined in BigBox as to which is the marquee you do not have to do anything special. I switch between quite a few themes and no issues (Critical Zone, Nostalgia, AON MQ7, and the new CoverBox to name some).