Why does Prism 3, by default, store printer settings properties in my project file? What will I lose if I change this option?

Prism 3 follows the Microsoft guidelines that provide for saving printer settings in the project file. This means that one Prism project or template could print on your desktop, another in the color printer down the hall, and another on a large poster printer somewhere on the network. You wouldn't have to choose the printer as you switch projects--the printer settings are stored inside the project. But few, if any, users take advantage of this feature, and it can cause a problem--some printer drivers are buggy, and saving printer settings to a file and restoring them when you open a file may cause Prism to crash. We added the feature in versions 3.02-3.03 (update) to tell Prism NOT to put printer settings in files and to ignore any printer settings it sees in existing files (make setting under "Tools... File & Printer Options" in version 3, under the "File & Printer" tab. This solves printer driver bugs, and doesn't really seem to inconvenience anyone

Prism 4 does not save printer settings in project files, but does save the page size. If you don't want this information saved in the file, choose the option in  Edit... Preferences...  File & Printer  tab.