Editing Mult-Choice Drop Downs

Hello, I am creating a quiz where the user will need to simulate choosing the correct choice from a system drop down. I have the question set up, however when I go to the properties of the drop down list it will not allow me to change the default background color or to select a default value to show. I have tried to attach a screen shot and keep getting an error, but I want to make the background a custom color and have 'select one' as the initial value. When I select the color and apply nothing happens, this is true with any color option. The initial value area grayed out and I cannot mark a check box. Can anyone help?

Thanks!

Sara