These instructions apply to the Setup Wizard and to the main Version Saver screen, which both display these lists:
To Move an extension from one list to another
This can be done by dragging and dropping the listed extension.
To Delete an extension from a list
To Add an extension to a list
From there, drag and drop the extension to either the "Backup" or "Don't backup" list.
VersionSaver comes pre-configured with a list of common file types, such as ".doc", which most people would want backing up. It as comes with a pre-configured "Don't back up" list. It is usually advisable at this program setup stage to scroll down the "Don't back up" list to see if there are any extensions that would would prefer to drag and drop to the "Backup" list.
The lists are very long and you may be concerned that file extensions that you use have been ommitted from the list. If so, don't worry. When VersionSaver comes across one of these extensions, it will add it to the "Undecided" list and pop up a reminder asking you to drag the extension name the the "Backup" or "Don't back up" lists, so it will know in future how to correctly deal with files of that type.