WIndows 10, Finale 26.x current
Well, I already have found a solution to my situation... but...
What I have wanted to do is hide the key signature while keeping the original pitches--with accidentals.
In this case, I have a piece originally composed in Eb, but because of so many accidentals and having to "show accidental" in Speedy Entry (asterisk), I decided to change the key signature from Eb to C (major for both).
I tried not transposing and checked "Hide key signature and show all accidentals"; transposing to C and "Hold notes to original pitches" with Enharmonically and Chromatically; and even checked "Transpose all keys proportionally"--just to try it.
The first option worked, but it did not preserve the "hide or show an accidental" with Speedy Entry's asterisk.
Then the lightening bolt came:
Use the "Edit Staff Attributes" and simply uncheck the "Key signature" box under "Items to Display" for every staff.
Voila! The key signatures disappeared, but all of the accidental remained.
Even so, is there a way to accomplish my original intent by changing the key signature?