Mail Attachment Downloader PRO Client or PRO Server
Manual settings copy:
All settings are usually stored in the %AppData%\MAD folder (open this in explorer or if you used command line args to specify a different folder, in that folder). If export/import doesn't work, you can try to manually copy settings from that folder.
Automatic backup of settings:
Automatic daily backups of settings are stored in %AppData%\MAD_BACKUP. You can import from this as well if for some reason settings were corrupted.
Gear Doc Converter
Manual settings copy:
All settings are stored in %AppData%\GearDoc. You can copy the contents of this to backup and restore the settings.