You can start updating an extension by downloading the latest version (.zip) from your dashboard-account under my downloads and follow the installation instructions below.

Note: Creating a backup is recommend and will allow you to revert back to a previous version of your Magento files if something unexpected happens during the extension installation. If this is your first backup, take additional care to verify that the backup is both complete and functional by performing a trial run of your recovery process.

Update Magento Extension

1. Disable Compilation
Navigate to System > Tools > Compilation. Check and see if Magento’s compilation mode has been enabled. If it has, it is vital to turn it off before installing an extension (or making any code changes). 

Note: In the worst case scenario, not disabling compilation mode before installing an extension could make your site inaccessible (including the admin area) so please check if it's disabled for sure.

Update magento extension

2. Turn on Magento’s Cache
Turn on Magento’s configuration cache – this will prevent Magento from trying to install the new extension too early. If the extension needs to make any database changes, triggering the installation too early could cause it to miss some database changes and create errors which are difficult to fix later on.

magento update extension

3.Upload the Extension and rewrite all files
Extract the latest version ZIP-file (using Winzip, WinRar, etc) and upload the app and skin folder to the root directory of the Magento installation. (You should not upload any other present folders within the supplied zip file, only these 2 directories).

All folders should match the existing folder structure. Make sure to overwrite the existing files of the extension. 

Note: Warning for Mac OS users using Transmit. If you are installing the extension in a local environment or you are using Transmit, make sure to merge folders and not to replace the existing folder's contents. Otherwise, your app and skin folder will be gone. Only rewrite extension files.
Same options as above. 

Magento update

4. Flush cache storage
Go to System > Configuration > Cache Management and click both the 'Flush Magento Cache' as well as the 'Flush Cache Storage' button. This is required to activate the extension.

Magento update

optional 5. Enable compilation again
When you had the compilation enabled before you started updating the extension you can now enable it again. Navigate to System > Tools > Compilation. Enable the compilation mode again and make sure that you run the compilation process again.

Magento check

6. Check Magmodules Extension version
Navigate to System > Configuration > Magmodules > General

If you can see that the extension is using the latest version you've succesfully done.