Start Audacity by double clicking on the program icon. This will open up your default settings and allow you to choose a new or existing project.
Select your options for a new file, or open a file you currently are working on. You do not need to have any music recorded before you change the bitrate.
Click on the main Audacity menu and a drop-down menu will appear.
Select preferences from the drop-down menu. A new dialog box will appear with several options on the left. The options include devices, playback, recording, quality and several other options.
Click on the Quality option. In the panel on the right there will be options for sample rate and default sample format. The sample rate should be at 44100 Hertz or higher for CD-quality sound. The Default Sample Format is where you can change the bit rate. Select from the 16-, 24- or 32-bit drop-down menu.
Click OK. You can now start using Audacity in the bitrate you have selected.