Yes, when I say cart, I am reffering to your Zencart web site which is a type of ecommerce shopping cart and is the part that the customer sees. Some people refer to it as their web site, others refer to it as their cart, some as their front end. I refer to it as the 'cart". The admin of course is what only You see.
The adjustment I told you to make
In your Admin,
Configuration->Maximum Values->Search Results Per Page
is ONLY for your CART, NOT the ADMIN.
However, since that does not seem to be working, try adjusting this to 20:
Configuration->Maximum Values->Products Listing- Number Per Page
I just tried that on my site, and it worked. It also shows up to 20 products in the products listing pages as well, but for me, personally, I can live with that. Try it, and see how that works for you.