This article applies to:
Codec Config may not save the settings when DirectShow (Async) is swithced to FFMpeg.
If a Save prompt is not shown when closing out of Codec Config, it did not Save.
Save without rendering the file.
If you would like to reset the settings to default, you may do so by going to Tools > Create Default Mappings > Selecting "Yes, remove existing mappings first > closing and saving.