How to turn off the reviewing, editing, and view feature?

The answer it wrong - the message that says she does not have permission is not correct, Just because the file is protected by "ready-only" from accidental delete or overwrite does not mean she does not have permission to edit the file if she chooses to do so. If you could examine the properties and acls on her file you would see what I say is true. The problem is this new "feature" in word which disables the basic functionality of how word has worked for the last 25 years of its existence. Until now, if you opened a read only document you could make changes to the text loaded into memory and decide later what to do with it. That is the way almost all programs work on windows, both now and for the last 30 years. I am amazed that Microsoft is not embarrassed that one of their flagship products has such a glaring mistake in such a top level message.

Just in case Chris - the Current Channel, not the Current Channel (Preview)? - both have the same build numbers.

And you opened Word a couple of document a few times?

I've just updated 3 machines (1 had the option, the other 2 didn't) to Version 2212 Build 16.0.15928.20198 (interestingly the Build shows 20198 at the end in the Account details and in control panel, but if you click on the About Word or About Outlook button the Build shows as 20196).

The one that had the Editing, Previewing, Viewing option still has it after the update.

So, no change!

Current Channel dropped today. The Viewing Button has disappeared! But they don't mention in the the Update notes. BUT they say:We often roll out features (and sometimes even fixes) to Current over a period of time. If you don’t see something described below right away, you can expect it soon.

Can anyone confirm that the Editing/Viewing button has disappeared?

No Paul. In the past you always were able to type into (or programmatically update) a read-only document, if it was not protected. You could not save it though.