Watermark on thumbnails

Hello,

I’m using nextgen gallery.
In Options>Watermark> I can stylize my watermark.
After that, I’m going to manage gallery, and I can watermark images.
I would like to know if it is posible to watermark only thumbnails.

Thanks for replies and bests regards from Spain.

https://www.ads-software.com/extend/plugins/nextgen-gallery/