Can someone please explain this?

I'm confused and need help.  Estimated OG is the expected gravity of the unfermented beer at the end of the boil, correct?  Now take your favorite Beersmith recipe and note the EOG.  Now in your equipment profile, change the loss to trub and chiller number to say 5 plus what it is now.  The boil volume increases by 5 gal and the post boil volume increases by 5 gal but the EOG stays the same even though you now have 5 more gallons and the same exact grain bill.  WTF am I not seeing??

Never mind.  I think I figured it out.  I need to adjust my brew house efficiency number because it just went to crap.

Bingo!  Volumes are based upon your inputs of batch size and process losses.  Sugar is based upon the brew house efficiency which dictates how much of the sugars from the mash make it to the fermenter.