Thank you for your post.
Pull down the View menu and select "Layout Mode". This then displays the layout and shows you the page settings. A thick semi-dotted line on the right side will show you the page width. If you then go into Page Setup, change from Portrait to Landscape and click OK, you will then see that line move, allowing you more room to print. The same applies for the height. You can use the Body part to move up and down to find the right page height that works for you.
If you run into any difficulty, or need clarification for any of the above steps, please let me know.
I have set up four scripts to address this problem.
You can then call the scripts each time you print. You would need to create additional scripts for Envelopes.
In FMP 10 you could use Layout Script Triggers to change the page setup when you enter a layout.
In previous FMP Advanced and Developer versions you can set up custom menus and call the scripts.
In other previous FMP versions I've used a print button that triggers the script and can be formatted not to print.
Remember that you can import scripts so you will only need to create them once.