A Blockchain is often said to be a log of all transactions that were ever verified on a network.
I understand that therefore a purpose could be to make sure that the records are not altered. If they would, the chain would fail by its construction.
However, what do you do when you have sensitive data that you want to store in these transactions? The reason I am asking is because the Blockchain being a Distributed Ledger, everyone has access to view all the transactions/chain.
Use case example: bank transactions
A bank could launch a Blockchain to make sure that the transactions of their clients are irreversible recorded. However, these transactions might contain sensitive information (like the details of their client). When a new block is created, the entire Blockchain is validated, meaning that the person who is creating the transaction has access to the whole chain and thus the details of the client in the previous transactions.
What is then the use case and how do people look at it this type of problem from their perspective?