Under custom send, should I specify the change address as the 1 and only address itself that I am sending bitcoins to? does this mean that  if I had 12 bitcoins in my blockchain.info hot wallet and I wanted to send 5 bitcoins to a paper wallet address, the other 7 bitcoins go to  a change wallet?  Im really confused because I thought the amount of bitcoins you have goes untouched, why would they turn into "change"??