I'm not talking about contractual control (which is largely mooted as pretty much every cloud service has a ToS that's grossly skewed toward their own interests over yours, with clauses like indemnifications, blanket grants to share your data with "partners" without specifying who they are or precisely what details are conveyed, mandatory arbitration, and all kinds of other exceptions to what you'd consider respectful decency), but rather where your data lives and is processed.
If you truly want to maintain confidence it'll remain private, don't send it to the cloud in the first place.