Right click on the file of interest from within Windows (file) Explorer
Select "Restore Previous Version"

If more than one version comes up, then grab a copy of each.
There is no option to keep more than 30 days worth of versioning. Mozy's current pricing structure does not charge for versions, so any increase would come straight out of their profits.
Some people that pay for MozyHome will
backup a computer,
uninstall the Mozy app,
drastically change the computer name,
reinstall the Mozy app
and backup again.
The first computer's backup should stay there as long as the account is all paid up. This probably does not work for MozyHome free users.
Another scheme is to keep your own local version control for a document - add a date to the file name, copy the document if you are going to change it, add a new date to that copy. Keep doing this for the life of the document and let Mozy backup each version.
Sig::: Practice restoring a file before you need a file in an emergency.
Using MozyHome (free) 2.20.3.276 on W7 Pro 64bit
http://mozy.com/home/download (file and release notes)
http://mozy.com/pro/download (file and release notes)