These are the only pages on the internet I can find with solutions:
https://www.macromedia.com/support/documentation/en/flashplayer/help/settings_manager07.html#117717
https://www.macromedia.com/support/documentation/en/flashplayer/help/settings_manager.html
I don’t recommend playing Red Rogue in the browser. Flash is obsolete and I don’t have the tools, knowledge, or money to keep a free game working. This project has not covered its own development costs in all the time it has been available (2012) so there’s only so much I can do.