How to turn off tracking (Grrrrrr)?

[Jennifer Murphy]

I am just getting up to speed on Word 2016 as part of Office 365. For some reason, Word just started tracking changes by putting red lines in the left margin for every change I make. I hate this. I never meant to activate it. And I cannot for the life of me figure out how to turn it off permanently. I have done

• Review | Tracking | Track changes | and unclicking Track Changes. I've even tried clicking on Lock Tracking, but it wants a password.
• Review | Tracking | Tracking | and unchecking all of the checkboxes. That turns it off until I close and reopen the document, then it's back on again. Grrrrrrrrrr.

How do I turn the damned thing off permanently?