Why do I need to unlock tokens?
Unlocking tokens authorizes the Balancer smart contract to move tokens from your wallet into the pool you want to join or execute a specific trade involving tokens in your wallet.
The token authorization is only needed once per token and is an inherent characteristic of the Ethereum Blockchain.
How do I unlock tokens?
Simply click the "approve" button and wait for the transaction to be confirmed as shown below (trade execution):

