Stay away from sites that are hard to audit, this is especially true of sites where you get a custom deposit address.  If you'r not able to see everyone eases deposit, how can you be sure of anything?  If you'r asked for a BTC address, it's vary much likely a scam.

Operators can take any public key script from the deposit's input and use it as an output, just copy the output the BTC came from.  Simple!

If you are using a web wallet "STOP"!  These are no good for the bitcoin network or ecosystem.  blockchain.info wallets are OK, make sure to have backups.

Changing the address for each round serves little purpose, as in the above 7dayponzi.com, this is likely a scam.