How do I invoice for a balance amount due?

I am using QB online and I have a tourism business. I have invoiced the client for the deposit of 20% which has been paid. I managed to do that invoice but can't remember how!!! Now I need to invoice for the 80% balance. In the deposit invoice, I had it all line-itemed with each line's quantity at 20% of the total quantity against the cost per item, for example, 0.4 as 20% of 2 of something, etc.

Now I need to generate the same format invoice but for the 80% balance. When I do try, it comes up with the exact same invoice structure, with everything line-itemed at 20%, but adds in the sales amount of the 80% as a line item.

What I would like to do, is have the invoice reflect each line item as 80% of the total, then add in the funds received, and show the balance due at the bottom.

Any help is greatly appreciated!