Start a NEW document and set all of the variables to the way you want them. Then save the document as a TEMPLATE file, using a name the you will remember, such as "NewD" or something else that makes sense. Now when you go to start a new document, use the new template and your setting will be the way you want them.
You can set-up different templates for different reasons, such as different customers or different drawing sizes. Whatever you feel comfortable with.
On other tip I use once I've set up my templates is to assign a keystroke shortcut to the custom properties screen so I can access its values with the press of a key instead of navigating through menus.