Hello Max,
If you have properly added a unique organ ID then the voicing adjustments any any other custom modifications you change should be retained.
How are you modifying the example no. 6 CODM file? Did you first copy it to a new file then edit that resulting file or are you editing the original file?
By default the original example 6 all frills unique ID is :
<UniqueOrganID>800005</UniqueOrganID>
Have you changed this to an ID not in use by any other existing CODM files? If not then you need to do so otherwise loading any other organ with a similar ID will overwrite the settings for the one you worked on if it used the same ID.
It's probably best to begin with the unique ID of 899999 which is not in use with the provided CODM files, then for each new file you create decrement that number by one, this way you are safe in not overwriting any existing IDs since this range is much higher and allows very many files to be created. Or feel free to check the existing IDs for all CODM example files then begin with a number above those and go upwards for newer files that you may create if that is easier for you.