Geany won't modify grub.cfg (Solved)

[tosim]

I guess I'm turning into a newbie! In "puppy", when I open an iso of a pup to make the changes from "pmedia=cd" to "pmedia=usbflash", using "geany", it does not allow the changes.Upon clicking enter, I get a popup about truncated errors, and it does not allow the "save".
Therefore, when I use the"make frugal app" to install the iso I get error message.This has happened with me using (installed on flash frugals)FossaPup64, BionicPup64, and a few others.I didn't have this problem with the editing in the recent past. I'm kind of at a loss now.
Would sure appreciate some assistance.Thank you very much.

[Clarity]

A concrete method

1. Open your ISO file via right-click

2. In ROX or your file-manager navigate to and open the grub.cfg and/or loopback.cfg.

3. Use a Geany or your file-editor to write your new changes into those file(s)

4. Save them in a NEW location/folder

5. Use isomaster (right-click on your ISO) to exchange the grub.cfg and/or loopback.cfg with the new file(s) that have your changes

6. save the new ISO that has your updated changes within

7. boot the new ISO or write it to external media; namely DVD or USB

This is the way I have always made my changes to ISO contents

[tosim]

What a quick, and helpful answer; THANKS. When I got to your answer #3, I (finally) remembered how I had always done it before(not with geany). I opened a text editor as admin, made the changes, and saved it, no problems.BTW-I did reopen that grub.cfg and checked to make sure my changes were there. Once again, THANK YOU. I will mark this solved, and hope I remember next time.