How to make all thumbnails CD covers?

hello dear Directory Opus
I want my all folder thumbnails like the top 4 folder of this screen shot. but I don't know why some of my folder does not show the thumbnails via the shell (provides 3D folder thumbs). those folder show the old boring thumbnails like the last 2 folder (Red marked) of this screen shot. how can i fixed that and show all folder like like the top 4 folder of this screen shot. Thanks everyone for help me.

There needs to be a folder.jpg or coverart.jpg in the folder.

If using folder.jpg, the majority of the other files in the folder need to be recognised by Opus as music files.

If using coverart.jpg, the other files in the folder don't matter and the thumbnail will always use a CD jewel case style.

You can change the coverart.jpg filename to something else via Preferences / Miscellaneous / Advanced: cd_thumb_coverart_file if you want to use a different name for forcing CD covers.

yaaaaaaaaaaaaaaasssssss!!!!
it's 100% worked for me. this is exactly what i want. I already have folder.jpg in every folder. Now i just Rename that folder.jpg file to coverart.jpg... voala!!!!! now its show CD jewel case style what i want. Thanks Dear Leo.