I’ve been looking in the settings but just can’t find it. When a camera is disabled, it shows just a blank grey screen. I want to change that colour that it displays. Where can I do that?
You can’t. Nor can you rely on your current result. If you’re not rendering a camera, the implementation is going to be different for each platform; in my experience, the general result is whatever garbage is in the color buffer. Unless you’re in the Editor, in which case it’s always grey.
Always use a camera.