There is no theme option to configure the lightbox.
If you want to have images connected through lightbox next/previous buttons you need to use the rel
attribute with the [styled_image] shortcode. All images with the same rel
attribute value will be connected through the lightbox’s next/previous buttons.
There is an example of how to do this in the documentation for the [styled_image] shortcode. → http://para.llel.us/themes/razor-wp/shortcodes/images/