I am struggling to add a block % increase to the products cost price and make it appear on an invoice.

Hi there, graham-gbbatteri.

In QuickBooks Online, you need to update the cost price through the Product and Service page. Let me show you how to do it.

1. Go to Settings, then Products and services.
2. Find and open the item you want to update.
3. Go to the Cost section and change the amount.
   
4. Once done, click Save and close.

The change or the new price will appear on the invoice going forward.

Or are you looking at a price mark up? If so let us know

For the discount, you can create an item and add it to the invoice. Here's an article as a guide: Add a discount to an invoice or sales receipt in QuickBooks Online.

I'm also adding these articles to help manage your products and services.

• Add product and service items to QuickBooks Online
• Set up and track your stock in QuickBooks Online.

Let me know if there's anything else you need about adding an increase to the product cost. I'll be right here to help you.