Reply to how to change the output channels for WHOLE OS (MAC)

I'm having this issue where i want to use my audio 8 dj soundcard and headphones through it, but finally after managing to change the channel (used to be 1/2) to headphones output (7/8) on the soundcard, the sound is still going through the channels 1/2 when using browsers(chrome, firefox), where VLC works fine with channes 7/8. I guess i need to change the setting on the browser so that it address the output to the channel 7/8? how do i do that?