Second version of FireFox can't be made default browser
I recently installed version 78.02 of Firefox as a second copy. The first copy is version 67.04. I left the older version as the default until I had the new version customized. I have tried to make version 78.0.2 the default version, but version 67.0.4 remains the default. I have tried both from inside of Firefox in the options menu, and from the program defaults in the Windows 7 control panel. Neither has any effect and version 67.0.4 remains the default. How do I get version 78.0.2 to be the default without uninstalling version 67.0.4?