Understand that a crossover is not a brick wall. It is gradual with a defined slope, probably either shallow (12 dB/octave) or steep (24 dB/octave).
If you set an 80 Hz hi-pass filter for your speakers, a slope of 24 dB/octave means that at 40 Hz, one octave below 80 Hz, your speaker still produce sound, but about 24 dB quieter than above 80 Hz. And at a half octave below 80 Hz, 60 Hz, your speakers will be about 12 dB quieter. You will hear something in the 60-80 Hz range from your front speakers, but you shouldn't hear much from them at lower frequencies.
Some receivers allow you to choose between steep or shallow slopes, and others don't.
As others have said, start by setting the crossover at 80 Hz, all around. See how it sounds, and then proceed by trial and error. Try setting it higher, say at 100 Hz, and lower at 60 Hz. Play with these settings until you are satisfied.