Mixing and Panning Tracks

Using the Track Controls

You can adjust volume and panning per track on the left-hand side of any track:
The Track Control Panel features a Volume Slider (+ to -) and a Panning Slider (L to R)
Note: If you collapse a track or make it vertically smaller, Audacity will hide the pan and volume sliders from view. To see them again, expand the track by dragging down on it's lower edge.

Using the Mixer Board

You can access the Mixer Board via View > Mixer Board.
This shows all track controls side-by-side, with a volume slider on the left per track, as well as per-track volume meters.
By default, the icon for each track is the Audacity logo, but it can be changed if the track name contains the following keywords:
Misc. instruments
String instruments
Percussion
  • acoustic piano, acoustic pno = acoustic piano
  • back vocal, back vox, bg = backing vocal
  • electric piano, electric pno, key = electronic keyboard
  • loop = loop track
  • sax = saxophone
  • synth = synthesizer
  • trumpet, horn = generic brass instrument
  • turntable = record player
  • vibraphone, vibes = vibraphone
  • vocal, vox = lead vocal
  • acoustic guitar, acoustic gtr = acoustic guitar
  • electric bass, bass, bs = electric bass guitar
  • electric guitar, guitar, gtr = (standard) electric guitar
  • string, violin, cello = generic stringed instrument
  • clap = handclaps
  • drums, dr = drum kit
  • kick = kick drum
  • perc = percussion
  • snare = snare drum
  • tambourine, tambo = tambourine

Rendering the Mix

Once you have your changes to mixing, panning and other real-time effects final and want to apply them onto the waveform itself, you can render the mix using Tracks > Mix > Mix and Render. This replaces all selected tracks with the mix. If you have used many tracks and real time effects, this may considerably improve performance.
Caution: When rendering, all tracks are added onto each other, which may cause clipping. If this happens, undo the mix and lower the volume for all of your tracks.
Best Practice: If you have a several stereo tracks, but don't need a stereo-effect for them (ie. any left/right panning), consider mixing down to mono using Tracks > Mix > Mix Stereo Down to Mono. Exporting a mono track to a lossy format (like MP3) will let you have a higher quality at the same bitrate, or let you use a lower bitrate (and thus lower file size) at the same bitrate.