[FMX04] Changing Background for a image with one click on EVERY scene - How?

Hi there, i was wondering of any of can helpme with this dilema i have.

I have set up ma flash project to have various scenes.
One of these scenes is a page whereby when a user clicks on a button he/she can change the background image on every scene in my project.

On each scene i have made a layer called ‘background’ and drawn a black rectangle which is the default background. This has been converted to a graphic using F8.

What i’d like to be able to do is when the user clicks on the button he/she can change this default background to 1 of 4 photo’s i have in my library.

i have tried the code:

[COLOR=Red]on (release)
{
colorchange = new Color("/rectangle");
colorchange.setRGB(0x0000FF);
}[/COLOR]

but all this does is change the colour of the background and not the photo i have in my library. Please also note i have to have this change applied to all my scenes.

I hope someone can help, Many Thanks