Going into settings didn't occur to you?
http://www.chess.com/home/livechess_settings
I agree. I have board set on maximum and it is still too small. It is fine for tactics and chess mentor , but not for playing. Also ,is it possible to get rid of the seek graph when playing a game?
Press and hold the "Strg" key (left bottom) and roll the mouse wheel (up).
Generally quite a nice feature. 
pls.make my board bigger