Turn on Track Changes by default

Are you saying that if you open Normal.dotm as a document and turn on Track Changes, you then cannot save it? FWIW, when you start editing and have forgotten to turn on Track Changes, you can save the current state of the document under a different name and then use Compare Document to compare it to the previous version. The markup will be the same.

After you have located the Normal.dotm file, to open it, you have to right-click its icon and choose Open (as opposed to New, which is the default action) from the context menu. But note that activating Track Changes in the template only affects new documents based on that template, which may not be what you want.

When I try to save Normal.dotm, it wants to save the file as "Doc2.docx." I probably should spend a few days on YouTube learning Word better, but all I use it for is simple editing of other people's text documents, and half the time I forget to turn on Track Changes.  I wish I could set it and forget it, and I can't believe others don't have the same problem.

Thank you for replying and also for letting me know abut the Compare Document idea -- that's a real life-saver.

When I try to save Normal.dotm, it wants to save the file as "Doc2.docx."

This suggests that you haven't really opened the file. When Normal is open as a file, the title bar says "Normal.dotm" (or just "Normal" if you haven't instructed Windows to display file name extensions).

But, as Suzanne wrote, the Compare function will be more useful if you have forgotten to activate Track Changes in a document you are editing.

As Stefan says, this means you haven't actually opened the Normal template for editing. If you have found Normal.dotm in Windows Explorer and just double-clicked on it, then you will have gotten a new blank document based on the Normal template because the default action for .dotm and .dotx (template) files is New. You would have to right-click on the file and choose Open. But here's another way to easily open and edit the Normal template:

In Word, press Alt+F11; the Visual Basic Editor opens. Press Ctrl+G to activate the Immediate window. In that window, type

     NormalTemplate.OpenAsDocument

and press Enter. Normal opens, but note that it may not be on top of all windows. You can close the Visual Basic Editor. Make the desired changes to the Normal file, and then save and close it. If the changes you have made have not been recognized as changes (the Undo button is not activated), press Spacebar, then Backspace to "dirty" the file, thus ensuring that the template will actually be saved.