How do I change the background image on the 5 day forecast?

How do I change the background image on the 5 day forecast?

generate the image using the latest version. You will see on the top of the screen image something like set background. Select your picture and it will change. I find that you will have to play with the font color and background until you get the right combinations , but it does work

OK - How do I set the background to no image?