Updating avg from directory
Either install the Update Channel Changer, or open Only the // on the first line is important because it is a comment.
If the value in about:config has still not changed, then right click and reset the preference - this removes the profile value that is masking the application one. This is no longer the case and in fact now that preference is almost ignored.
For example, on Windows 7, the files "active-update.xml", "updates.xml", and the "updates" folder can be found in one of these locations  (using Firefox in the first example).
Note: You'll need to show hidden files and folders to find these locations: A Software Update "Update Failed" error, Something is trying to trick Firefox into accepting an insecure update.
The application will need to restart to apply the update, but you can choose to restart later by pressing the Later button.
Software Update problems can sometimes be resolved by simply restarting the computer and then reopening your Mozilla application.
This is so the application always uses the same updates regardless of what user profile you are running with.The application may be non-functional and/or result in your profile being corrupted.See Profile_backup for information to safeguard your data, and see the daily builds threads at the Mozillazine forums for the current status of the builds: Firefox, Thunderbird.Related bug reports include: Updates can be retrieved from a number of different update channels.To check which channel you are on, look in about:config at app.update.channel.
Note that you cannot change channel using about:config.