Captions / Description

Hi,
I don’t have much experience working with NGG but i host and manage a website for a client that uses this plugin.
He contacted me about a week ago to say the images have stopped displaying the image description that he had entered a while ago. This description used to display on the main sized image once the thumb had been clicked.
I am assuming this is down to the recent plugin update but i cant for the life of me find anyting in the documentation advising on how the get the image descriptions to display.

Can anyone help please

Thanks

http://wordpress.org/plugins/nextgen-gallery/