MSWord documents open in window that is too small and short

iMac running High Sierra and MSWord 16.25 on a 365 subscription. A few weeks ago when I open a document, whether a new one or existing, it opens in a small and short window. I can expand to the size I want, but it used to open in a reasonable sized window that was as tall as my screen. Now it is only 1/3 the height of my screen.

It is driving me crazy. I have tried deleting the normal template and then opening, sizing a window and then saving the document, then closing MS Word. That fixed the width problem, but not the height problem.

Someone suggested clicking the green button on the top left. That's great if I want full screen - which I don't, but does nothing to change the size of the window that opens next time.

Help please! Thank you in advance.