https://usermanuals.finalemusic.com/FinaleMac/Content/Finale/Articulations.htm

If you edit the duration, it will affect all of the fermatas in the score. If you want a different duration at other places, create duplicates. You might also Google <fermata duration finale> and look at a number of comments.

Thank you. I got the fermata to hold the note longer, but for some reason one voice sustains longer after the other voices release. Any idea what is causing that?

Fermatas traditionally increase the length of a note by a percentage of its value, so a fermata over a half note will increase its length by more than a fermata over an eighth will.

I have entered different numbers into the Top Note Value box (up to 500%) and the music doesn't stop at the fermata. Should I enter values into the Bottom Note Value? I don't see much explanation in Finale's help section. Is there any way I can send a file to you? 

Thank you!

I always put them in both.