“General” settings tab options.
Post Gallery comes built-in with a light-box (Swipebox) solution that will allow any media to be viewed full-screen on click. When this options is un-checked, Post Gallery will not load in the site the assets needed to run the default lightbox. This options is useful if you wish to change and display a different lightbox solution.
Every gallery created using Post Gallery is managed inside a post. In WordPress a post can be a Blog post, a Page, a Product or any other type of data, this categorization is identified as a post type.
Post Gallery allows admins to specify (with check-boxes) which post types will allow galleries and which don’t.
When editing a post, the gallery option will be displayed as a metabox below the content editor. This option will allow admins to specify the context and priority in which the metabox is displayed (read more in codex).