It was never clear to me.
After i sent some Btc, 'change' goes to a unknown address. How can i know previously this address ?
How happens 'changes' process???
Bitcoin-Qt (aka Bitcoin Core) automatically generates 100 change addresses to start with, and refills the pool when it gets low. Change addresses are handled transparently to the user, so you won't find them unless you go looking. If you want to see which of the addresses in your wallet contain coins, enable coin control and look at the individual inputs when sending a transaction. The
Bitcoin Wiki has more information on how change addresses work, if you're interested.