Bitcoin-Qt help and changes

i am using Bitcoin-Qt on windows, it ask for data directory for the first run, and now i want to change it to another folder, but sadly i can't locate its config file, on the web it say it is C:\Users\<username>\AppData\Roaming\Bitcoin but nothing there. i am running windows 2012 server, i need to know the configure file of bitcoin-qt, if it is hardcode, i need someone to change the code to allow custom configure file. Also help me to download to 80GB blockchain data file. no time waster please.