Big Screen should work fine with the default settings on Windows, however we do recommend a few things to make everything seamless.
Big Screen should work fine with the default settings on macOS, however we do recommend a few things to make everything seamless.
Ensure that Displays have seperate Spaces is checked. If this isn't checked then its not possible to extend to seperate screens: System Preferences > Mission Control > Displays have seperate Spaces
Set a black wallpaper for main screen: System Preferences > Desktop & Screen Saver > Solid Colours > Custom Colour
Disable screen saver: System Preferences > Desktop & Screen Saver > Screen Saver > Start After > Never
Turn on Reduce Motion to prevent screen sliding across when going fullscreen: System Preferences > Accessibility > Display > Reduce Motion
Automatically hide and show the menu bar to prevent it showing up on the main screen: System Preferences > General > Automatically hide and show the menu bar
To play YouTube videos with Firefox the Autoplay sound permissions needs to be set.