[MlMt] Where is the list of fields? e.g. ${#source.path} (to customize Downloads Sub folder)

[Jeff Newman]

>> Wow, another amazing power feature discovered today. I noticed in Settings-General that there is an option for Downloads to be saved in a Sub folder. The default path is: ${#source.#name}/${#source.path}

I had no idea that existed! I can't seem to adjust the default save path. Is this affecting anyone else? Is there something else I need to do to make this editable (I have put a checkmark in the box, but the field isn't editable)

Jeff.