There is no official "switch" in the preferences. If you see links online claiming to provide a "Dark Mode" patch or link for Flash CS6, be cautious: Third-Party Extensions
October 2023 Target software: Adobe Flash Professional CS6 (Final standalone version before Animate) adobe flash cs6 dark mode link
Check Edit > Preferences > User Interface (Windows) or Flash > Preferences > User Interface (Mac) to see if brightness sliders exist. There is no official "switch" in the preferences
If you are strictly limited to using Flash CS6 (due to hardware constraints or legacy workflow requirements), you must rely on your operating system’s "High Contrast" settings to simulate a dark mode. However, for a seamless, professional dark interface, migrating to Adobe Animate is the only official solution. for a seamless