I’m not seeing Corteza Studio where I can set the site branding- am I looking in the right place? This is on a chrome browser on a Mac offline hosted.
Your screenshot is just too small to see if you have the tabs to theming. Next to this “General” tab there are 2 other tabs: Light and Dark.
Can you see them?
Ok, you might need to upgrade your instance then. You might be using a slightly older version without the theming tabs you can see in my screenshot.