having trouble creating external link for gallery.

Hello all.. I have searched for a couple days now and still cant seem to figure this out. I am trying to have the lightbox open in a new window or tab but can not find where I need to change “_Blank” So when I insert my gallery into a page it looks like this..

<img class=”ngg_displayed_gallery mceItem” src=”http://shawnjollyrawphotography.com/nextgen-attach_to_post/preview/id–20967&#8243; alt=”” />

thanks for any advice on this matter..

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