Blockchain – Create an account and transfer usdt to your wallet address. We use blockchain to retrieve addresses. Why did I use an address before I created my account?

There is an app called kzzy. You can fund your account with btc, eth and usdt. All cryptocurrencies are converted to usdt once transferred to your account. You are given two wallet addresses to send your cryptocurrency to. This is an eth address that matches the usdt address and the btc address. When I searched for this address in Blockchain Explorer, I found more transactions than I did. There are transactions that exist in your wallet address before creating a kzzy account. Also, like on a futures exchange, you bet on the high or low contract for BTC via USDT. However, there is no record of the contract transaction #. Also, I can’t find any contract bidding records for this kzzy app on the blockchain. Only transfers and gas fees from my personal wallet to the kzzy account wallet are displayed.

My two questions are – Can I safely reuse my wallet? -Is there a transaction record of futures trading pool contracts on the blockchain?