I'm on a Mac 10.15.3 (Catalina) running CC 2020, and to my dismay the Manage Sites dialog box / window is not available. I define new sites all I want, but if I want to change something about a site already defined, I cannot get the Manage Sites dialog to appear. How do I fix this?
Did you uninstall old CC software before you upgraded to Catalina and then perform a clean install of CC as recommended?
Try Restore Preferences.
Before Catalina I was running CS6
You didn't answer my question.
Did you uninstall old 32-bit software BEFORE installing Catalina?
If not, you may have problems until you manually get rid of them.