It is very likely that your old overrides are not needed or useful anylonger.
New template technics: Virtue Mart 3 uses a slightly changed database layout of VM2.
It is very highly recommended to keep your software updated, as it typically improves security or functionality.
I recommend performing a Full Backup before proceeding with this or any software update, so you can roll back an update if it causes issues.
Make sure you download the Manual Installation Package for Joomla.
Then you should upload the package to your account. Please make sure you backup your files and your database.
There are some critical issues in the encryption functions in the php5.2 versions.
," in this tutorial we will show you how to perform a software update.
There are some tasks which should not be done automatically and which can throw errors. Use the tool "Remove old vm2 inherited customfields". It works for some people quite well, for others not.
The purpose is to remove customfields, which are in childs and just overriding the default one of the parent.
Upgrading your Virtue Mart Joomla component is quite easy and straight-forward.
First, you have to download the new Virtue Mart package from the official website.