flash and shutter speed override ?

[Village Idiot]

You should really invest in a book like Lifght Science & Magic. It's like you're trying to cook a meal without knowing how to use the tools.

The inverse square law applies to everything the light touches and not just your background. It applies to the subject, the tables and chairs in the room, etc... How close any of these objects are to the light source determines the exposure of the light on them.

Try the lighting 101 section on strobist.com to get yourself started with some good free reading.