Grey shading across top line

I have managed to create a score where the top line of the music starts in the grey shaded area of the page. I have no idea how I did this! It extends across every page. As a result, the treble clef part of the organ is in grey and the bass clef part of the organ is in white. I tried changing the page settings but that doesn't resolve the problem. It is most frustrating and I think this problem is also affecting my ability to fix other problems I am having with this score. How do I push the music down into the white area? Or do I need to pull the white area up above the music??
Many thanks for your help.
Chris