Whenever I record audio it was either very low volume or it is just recording the right channel (only my right box will output sound).
My settings are full volume input, ALSA as Audio Host, pulse as Output device and pulse: Font Mic: 0 as Input device. And Input channels are set to 2 (Stereo Input Channels).
What did I do wrong? Is it even possible to record 384 kpbs high quality with audacity?
I doubt that you get as good as “CD quality” from most sources. On-line audio is usually much lower sound quality than a CD.
To get audio from a video file, the best approach is to digitally extract the audio.
For many file types, Audacity can do this by importing the file IF a suitable version of FFMpeg is installed, (which I don’t think is possible on the latest version of Ubuntu or Mint).
Other applications are able to extract audio from video files. For a command line program, see the documentation for “avconv”.
By default, Audacity records as 32 bit float format, uncompressed PCM, at 44100 Hz sample rate.
Compressed audio formats such as MP3 trade off a certain amount of sound quality against keeping the file size down. The highest standard bit rate for MP3 is 320 kbps.
There is more information about file formats in the manual: Audacity Manual
The way that I would recommend recording audio that is playing on your computer, with Audacity on Linux, is to use PulseAudio “Monitor” input. See the link in Gale’s post.