hello this won't be possible, since the name property of the digitally signed executable file are used by windows to show the program's name. maybe there is some sort windows tweak that allows altering of the names displayed in the volume mixer, but i doubt it...

So can't we change the name of that digitally signed executable file?

then the signature will obviously be broken - i don't really know what backlash this will have, but it's definitely not worth the hassle (possibly windows giving error messages, anti-virus programs might report it as some threat and there might be problems with the firefox update mechanism, not to mention you'd have to repeat the procedure after every new update).