You need to store the value as a preference that gets saved in the config files, like the values in the option menu, they start with &pref like those:
https://github.com/GarageGames/Torque3D ... lts.cs#L28
Only they are saved to a file when you set them in the game. Maybe you forgot to write into the script a function that saves the values to a config file, happened to me before, I just force save all the values when the option dialog is closed so it never forgets to save the changes.
You also need to make sure to use the &pref value instead of anything else when setting the camera view distance for the first time.