In Finale, triplets are form of Tuplets. The Quantization Tool is used to make Tuplets even. I would start here and follow the links.

https://usermanuals.finalemusic.com/FinaleWin/Content/Finale/Quantization_Guide.htm?Highlight=tuplets%20hyperscribe 

thank you, Mike, for directing me to this important link.  Altering the settings did produce correct 1/8th note triplets, which is a welcome relief.    However, the settings do not work for quarter-note triplets.   I was inputting "Speak Low," which is filled with triplets last night, and had to do it using Speedy, which is far slower.

By the way, I tried to supply you with a screen shot of the results but received the msg "you can only upload...,"   even though the image is a .gif weighing a mere 7 KB.   Can you help with this?

Screen shots need to be a jpg or png. If you're on a Mac, you can open the graphic and select Export in the menu below, then select the type. Do not select pdf — those cannot be attached either.

… I tried to supply you with a screen shot of the results but received the msg "you can only upload...,"   even though the image is a .gif weighing a mere 7 KB …

That has happened to me a few times.

Usually the culprit is that I have spent too long time while writing my reply.

This fix works for me:

Select the {reply text}, copy it to the Clipboard, go back to the thread, and and start all over again, with a new reply.

Paste the text from the Clipboard, and attach the graphic.

When I have had difficulty posting an image (and it is a real pain), the solution suggested by MM was to clear recent history (IIRC).