Can we change the page format to A4?

Good to see your post here, tropicaflore-int.

I can assist you with changing the page format to A4 paper size for PDF attachments in QuickBooks Online (QBO).

To make sure it prints on A4, you can follow these steps:

1. On the left panel, click Sales.
2. Go to the Invoices tab.
3. Click to open the invoice.
4. Click Print or Preview.
5. Click the Print or Preview option again.
6. Click Print.
   
7. Click More settings.
8. Click the drop-down arrow next to Paper size.
9. Choose the A4 option.
   

In case you need future reference into printing issues, you can visit this article: Fix QuickBooks Online printing issues on browsers for Windows.
 

Let me know if you need additional assistance with printing in QuickBooks Online, and the Community will be sure to get back to you.