You can change the number of images in almost any Posterino document. The initial number of images right after creating a new document from a template is just a handy start configuration.
There are several ways to change the number of images:
Change the number of images by using Drag & Drop:
You can of course apply the operations above to a set of images.
Change the number of images using the Inspector:
Locate the properties panel of the current layout method. E.g. the panel:
Grab the slider and change the number of images to the number you plan to use:
Alternatively you can define the grid of images by changing the value of the and properties.