Why is the wallet address different every time?
When using The Giving Block widget you'll notice that a new wallet address is created every time. This is because The Giving Block uses dynamic wallet addresses.
This is done to protect both yours, and the nonprofits privacy that you are donating to. Doing so helps prevents third parties from viewing all of your transaction history simply by copying and pasting the wallet address or TXID into a block explorer.
All addresses that are generated are associated with your donor information AND the nonprofit forever. This means that you can reuse the address as often as you'd like or you can generate a new one each time. It's up to you. In some cases, users want to re-use an address because they've added it as a payout address in an app or smart contract. Note that for ETH, after the first donation is sent, the address is converted to a smart contract.
The address is associated with your donor information so that every time you donate, if an email address was provided, you will automatically receive a receipt as soon as the transaction is confirmed on the blockchain.