Why is Word sending confidential words from my doc to Bing?

[Arkwright]

Help - I have just re-opened a company confidential financial document and a pane has appeared on the right-hand side in which passwords from the docx have been sent to Bing. It's like discovering someone in the bathroom after a few minutes. (Obscene behaviour by MS: completely untrustworthy.) I have a couple of questions (hope someone can help):



1) How do I stop Microsoft snooping in my documents and sending confidential bits of it over the internet?
2) When did this start happening? (We need to audit the system to see which confidential info might have been compromised. Mega job.)
3) If we want company docs to be secure is the only safe way to switch away from MS?

We deliberately bought several W7 PCs rather than W10 because of privacy/security concerns, and stuck with Office 2013 for the same reason. We've started switching to Linux because of this worry about MS changing to Mass Surveillance Google business model: I would be very grateful for any views on whether we should switch completely from MS now to secure our company.

Many thanks for any help!