In the video for the blog post how to add your own backgrounds, I mentioned you can select a category for the background you were adding. You could add the background to an existing category, but the pix2print software also gives you the option of creating your own category.
Now imagine you want to add quite a few of your own images or photos as backgrounds. Creating your own category makes sense as you can then select that category in all photobooks of that size to show you only your own backgrounds.Or you might have so many backgrounds you want to use that you want to categorise them even more, for example create a separate category for beach holiday and snow holiday backgrounds.
Create as many categories as you need and select the one you need when you create your next photobook. And remember, adding backgrounds is done for a specific size photobook, if you want to use the backgrounds in another size add them to that size too.