Why when I send an invoice with an attachment my customer only sees attachment not invoice?

I've got the steps to display both the attachment and invoice in the email, @lennesbros.

You can enable the Show full details in email, PDF Attached, and Online invoice options. Here's how:

1. Go to the Gear icon and select Account and settings.
2. Open the Sales tab.
3. Look for the Online delivery section and click the pencil icon.
4. Choose Show full details in email.
5. Tick the PDF Attached box.
6. Under the Additional email options for invoices dropdown, pick Online invoice.
7. Hit Save, then Done.

Also, you can check out this article for more guidance on receiving and recording invoice payments: Record invoice payments in QuickBooks Online.

I'm still all ears if you need further help with your invoices. Just add your reply below, and I'll be there to assist you.