The Lightbox Plus Image Viewer Plugin Settings
The Lightbox Plus Colorbox Plugin is the feature that expands your images when you click on them vs opening them in a new window. We do not suggest you edit or deactivate this plugin unless you have the knowledge to do so. If you do want to access the settings, they can be found under APPEARANCE > LIGHTBOX PLUS COLORBOX
To Activate
Head to Plugins > All Plugins and look for the Lightbox Plus Image Viewer to activate it