Fortunately you don't have to uninstall and reinstall Audition to do this - although that's certainly an option. Bear in mind that doing this will only work if you choose to delete your preferences as part of the process.
There are several other options though, and I suggest reading through all of them before deciding which to use. We'll start, though, with the other simple one. If you start Audition with the 'shift' key held down, this will achieve the same result - the preference files won't be read, and the default (aka 'vanilla') ones will be reinstated. Certainly with a Mac (and probably a PC as well) you have to hold the 'shift' key down at least until the splash screen appears, otherwise it might not work.
From here on, it gets a little more complicated, but you get more options. The reason for this is that in order to get at the individual preference files, we have to consider three different operating systems, XP, Windows 7, and OS X. By default, in all of them, the location of these files is hidden, and you have to reveal it. When you have done this, the path and files will be revealed.
Revealing hidden folders:
XP: In a folder, go to Tools>Folder Options>View and scroll down to the hidden folders entry. Select the 'Show' option. The path to the Preferences folder is C:\Documents and Settings\[user_name]\Application Data\Adobe\Audition\5.0
Windows 7: In a folder, go to Organise>Folders and Search Options>View, and then it's the same as XP. The path to the Preferences folder is c:\Users\[username]\AppData\Roaming\Adobe\Audition\5.0
Mac OX: The Preferences are in a library folder, and are apparently stored twice. The locations of them are:
There is a note about this at the end of this FAQ*.
Anyway, there are, apparently, several ways to unhide them:
1. The easiest way to get there without opening Terminal is to open Finder or click on your desktop, click Go in the menu bar, then hold down the OPTION/ALT key. You should see Library appear in the menu as long as your holding that key and clicking the menu item will bring it up in Finder.
2. Use Command+Shift+G from the Mac desktop (or Finder>Go>Go to Folder) and type in ~/Library to temporarily access the Library directory. When you have finished manipulating the relevant parts of it, close this window and the folder will no longer be visible.
3. To make the Library folder visible permanently (like in OS 10.6 and earlier), open the Terminal application and use the following command: chflags nohidden ~/Library/
What do you have to do when you've revealed the folder?
The basic idea is that if Audition opens, and it doesn't find a particular file in the preferences folder, it recreates it. So, you can either delete all the files in it (the same as Shift+open), or you can be more selective. Primarily there are three .xml files that you are interested in, and if you are only having a problem with one of them, then that's the only one you need to delete.
Application Settings - deleting this will restore most of the settings in the program itself back to defaults
Effect Presets - deleting this will restore default settings, but if you have made any of your own presets, you will lose these too.
Favorites - the same as Effect Presets, only for the Favorites list.
There is also an .xml file for Machine-specific settings, but this only affects your sound device, and generally would be rewritten anyway if anything changed, so generally doesn't need to be touched. Mainly it's the three I mention above that are the ones you will be interested in.
* A note from Durin about the Mac preferences files:
"The directory path, ~/Library/Preferences/Adobe/Audition/5.0/ is where we store all the preferences, presets, workspaces, log files, etc. Anything and everything a user may need access to. The .plist file is more of an application/OS level preferences - similar to an ini or registry entry in that it's less user-facing and more preferences for how the application works with the OS. In Audition's case, this stores information such as the last directory accessed, File Open/Save dialog dimensions, and other mysterious prefs that are just random GUIDs that Audition and OS X understand.
In either case, if the directory or .plist is missing, it will be rebuilt on launch to the first-launch defaults."