MAKING THE SCORE SIZE SLIGHTLY SMALLER?

I am working on a score for Symphony Orchestra and on the
opening page, where all the instruments are playing, the 'Cello
and the Double Bass are sipping off the bottom of the page.
I have tried tightening up the space for each stave but it is still
not fitting on the page. I am thinking of reducing the size of the
staves slightly - but I can't find how to do this. Any ideas?
Jeff