To enable more than 4 products (scrolling or randomized display) you need to add some code.

In this tutorial it is being referred to as 4 ads at a time. When you add multiple it is about randomizing between those 4+ ASIN's you add, but only 4 at a time will be displayed on your site.

Thank you! I found the code to randomize.

Here it is in case anyone else needs it:

amzn_assoc_random_permute = "true";