Raspbian Stretch - Updating alsa options
All we have to do is tell Raspbian to look at "card #1" for the default audio. Card #0 is the built in audio, so this is fairly straightforward.
Tun sudo nano /usr/share/alsa/alsa.conf and look for the following two lines:
defaults.ctl.card 0 defaults.pcm.card 0
Change both “0” to “1” and then save the file. That’s it!
Raspbian Jessie - Updating alsa options
Earlier versions of Raspbian store sound settings in different places, with different syntax…
For Raspbian Jessie, run sudo nano /etc/asound.conf and put the following in the file and save:
pcm.!default { type hw card 1 } ctl.!default { type hw card 1 }
This will make the default PCM (audio) output card #1 and the default control also card #1
Raspbian Wheezy - Updating alsa options
If you're using Wheezy, we'll edit the audio system configuration file with
sudo nano /etc/modprobe.d/alsa-base.conf
For all but the most recent Raspbian Wheezy releases, look for the line that reads:
#options snd-usb-audio index=0
Change this to:
options snd-usb-audio index=0
Note we removed the # at the start of the line.
For the latest Raspbian Wheezy versions, look for this line instead:
options snd-usb-audio index=-2
There's no # to remove in this case, just change the index from -2 to 0:
options snd-usb-audio index=0