I turned "numeric order filename sorting" off several times already for a particular folder, but after some time it seems to get turned on some way or another. Two questions:
Is this a bug, or is there a way to make the change permanent?
Is this a setting per folder, or for the whole file system?
It's a per folder setting, but through the dialog you can also set it globally. After you have made your changes, did you save that setting in the folder options? Preferably for all subfolders & layouts?