Hello
Is there a way in Opus to change the default folder icon without going through Windows and the registry?
Thank you
Doing it via the normal registry method is best, since that'll only change the default folder icon, not the icon for every folder, and it'll also change it system-wide, not just in Opus.
But you can also create a label which matches all folders and overrides their icons, if you want something which is Opus-specific. That can be done via Preferences / Favorites and Recent / Labels and Label Assignments.
thank you to you Leo for this answer through the preferences 
hello Leo
actually I went through the W10 register to modify icons by default I was afraid that dopus "does not see it" so I just have to change some icons by hand through the preferences as you told me. 'said, thank you again for your answer
Francois