I use Flat Fee so I'm not familiar with the global billing options...does this help at all?
The link looks weird I know, but it looks like it walks through the billing settings prety well.
http://http-download.intuit.com/http.intuit/CMO/proseries/resources/user_guide/ty08/3%20-%20Setting%...
♪♫•*¨*•.¸¸♥Lisa♥¸¸.•*¨*•♫♪
