Saving your stories

I've been working on some very large stories but am quite frustrated with Windows 10 file management protocol. It feels like they do sinister, and sneaky things with file preferences; seeming to try to put things on their "sky drive", which to me means out in the public. I do not trust them. I "think" that I now understand enough about what to look for each time I save a file, but there is always the feeling that some sneaky geek will change things and I will miss that.

I write in MS Word 2016, um because that is what I have, and I am no computer Master at all, nor do I wish to be. For me it is about the story and nothing else. So, armed with the, still uncertain, confidence that somewhat reliable file management is possible, before I get on with the latest project, does anyone have suggestions?

Ahabidah