Allowing users to change the withdrawal address or even displaying it is a serious security flaw so please don't forget which withdrawal address you have used.
I suppose that's true. I usually keep a note I just forgot to save when I restarted. My wallets sync to one client, so knowing the address just helps so I can look it up on the blockchain. There is about 8 possibilities for what address I entered, but none have received 0.58 BTC yet. Hopefully you get back to my PM soon.
Ok, but why wasn't there a drop in the amount invested as well? It stayed around 89.5 the entire time.
Well, that's the bankroll, not the amount invested. If someone were to lose at the same time an investor withdrew the same amount, the bankroll would stay the same but the % of each investment would go up a little.
