Something happened. I can not use copy & pasta in the invoice section. It worked for years now it don’t.

I can think of two possible scenarios based on your invoice concern, Chapdav2. I'll explain each one in detail below.

If you want to copy an invoice, there are two ways to do so within QuickBooks Online (QBO). You can either open an existing one and select Copy or navigate to your list and select Duplicate from the dropdown menu.

To make a copy of an invoice, here's how: 

1. Go to Sales and select Invoices.
2. Find and open the invoice you wish to Copy.
3. Click More at the bottom of the page and then select Copy.

To use the Duplicate option, please see this article for the complete guide: Duplicate an invoice or an estimate in QuickBooks Online.

On the other hand, you should still be able to copy information from outside QuickBooks and paste it into the invoice. If you're having trouble with this, I'd recommend performing some troubleshooting steps to refresh the system.

Additionally, once your customer pays an invoice, you need to record it to balance your accounts. You may want to check out this article as your guide: Record invoice payments in QuickBooks Online.

Please let me know if you have any other concerns about managing invoices and sales transactions in QBO. I'm always here to help you out.