If you need to change the paper size you are printing on, go to Page Setup on the right hand side of the preview window.
Under the Page Setup button, you can see a button that says Fewer Options. If you click on it, you will see that all the options you see under the preview pane will disappear. Those options are usually not needed unless you are setting up your document for professional output. I will go over those very briefly, but I will not get into those ones very much at this time. When the extra options are not shown, the Fewer Options button toggles to More Options.
Under the preview pane, you will see a drop down menu. By default it should be set to Colour Management, but you will see that the pull down menu offers also another option, i.e. Output.
