I don't have any code that changes the config file.
I'd look here at the concepts:
https://www.afralisp.net/autolisp/tutorials/file-handling.php
Then read the entire file into memory.
Search each line for your setting.
Change the setting
close config file
create a new file to overwrite the existing config file

Once you update the config file it can be shared with others to use the same file.

Usually, the settings only need to be set once, so you can just set them, then put the file in a location all users can see.