How did you set up this document? Did you use one of the templates?

I honestly can't remember; I was just fumbling.  I think I just used the "default document" option.  I just now tried to start a new one and the chord suffixes were there, meaning the library was there, so  don't know what happened.

Let me ask another question, which may resolve the issue:  how can I create a new document using a simple lead sheet, with 4 measures per system and no indent on the first system (I don't see the point of opening a new file with an indented 3-measure system, but I'm not a classical player).  I think once I set up a lead sheet like this, I may not have a problem with the chords.  I did try to figure this out from the manual before posting here - to no avail.  Thanks for your help.

Let’s start here: Open the default document template. Do the chords work properly? If they do, then you can make the changes you want, and save that as a template.

Here's another option. From Finales file menu, choose open document from template. Then open the General Templates folder. In there you'll see 2 leadsheet templates, one has the handwritten look, the other is standard engraved. Choose one and try that. If you need to make more changes. Make the changes to this file, then save it as your personal leadsheet template.

Could it be that the first time, you have created a New Document without libraries, which is one of the options ?