It's very possible that you won't be able to see/print everyone at once on a large family tree. But you can maximize the number of people that you see by changing some of the options. Click on "Show options" at the bottom of the screen, and change Parents, Children, and Others to the max. You might have to click on different people to see which person gives you the widest coverage.
For instance, if your tree is primarily all of the descendents of someone, click on that person. If it primarily all of the ancestors of someone, click on that person. For a more varied family tree, you'll have to experiment.