Hi there,
Thanks for writing in! It would be best to update your theme and cornerstone to the latest versions so everything is up to date. Make sure you have a backup of your site before proceeding.
To check the latest versions, please visit our Changelog
Note: That you may need to delete Cornerstone manually via FTP if the update is not showing up. Updating X to the latest versions should install the latest Cornerstone in the background automatically.
Let us know how that goes. Hope this helps – thanks!