See Making Forms with Microsoft Word which may give you too much information.

There are several ways to do what you want. If this will only be used in Word 2007 or later, use Word Content Controls and restrict editing to no changes allowing your content controls as exceptions. Both the content controls and the editing restriction can be found on the Developer Tab.

Charles, thank you, I will investigate those options. I do occasionally need to make other changes, so it looks like I will need to research the "too much information" link.

You can make changes by undoing the Editing Restrictions. You can set a password on these. If it is just for my own use, I usually do not set a password.

Well, I made my first form using the text boxes in the Developer tab. I had to turn my document into a template and start using the updated Word (had been using an old version). It did take some Google to figure out the details of the process. I have been using just simple functionality for so many years!

Anyway, it appears to be working. Thank you Charles!