Problem making buttons remain on the edge of the sreen

I’ve built my first flash application and it’s very close to being finished. I have a problem with two buttons that are on the are on the left and right of the stage. When the browser is enlarged these buttons don’t remain on the edge of the browser. Anyone know how to do this?

Not sure if i explained that very well so here is a link to the application http://newmedia.leeds.ac.uk/ug08/cs08j3h/tom_thumb/tomthumb.html if you make you browser wider you will see my problem.

Thanks in advance