Thank you both for your recommendations. I think I solved the problem by drilling down further into options.
FYI: "Flush left/right, center stack or justified" are older graphic design and typesetting terms that mean the same things as "Align left/right, center text or justify". Sorry for the confusion.
The solution I finally discovered relates to the options on the ribbon at top of worksheet window. Under "Merge & Center", I tried "Merge Cells". That retained the left alignment previously set. Then I selected the row and selected "Auto-Fit Row Height". Voila. I thnk that did it.
The problem I was having related to confusion about how the different options worked under "Merge & Center". Perhaps this was due to experience with older versions of the product. I'm still confused about the fine points of how the various options work under "Merge & Center" (i.e., "Merge & Center, Merge Across, Merge Cells"), but don't have time to work on it any more. Anyway, perseverance solved the problem this time.
I like this product, have used it for years but not professionally. Keep learning as I go.