Thank you very much. That is the correct listing in the mame.ini.
I didn't realize it would be a different naming convention from the on screen setting.

I have found phosphor resistance, red (green and blue) set to 0.10 to my liking after setting them in the on-screen slider options.

I'm unaware of how to write these correctly into the mame.ini to save the settings.
If this is possible, I would appreciate any help.

Thank you.