I can provide some ways on how you can review where you've sent your invoices or quotes in QuickBooks Online (QBO), northernlight.
You can double-check who's the receiver of an invoice or quote by navigating to the All sales window. Here's how:
- Go to Sales, then All sales.
- Modify the Transaction type and Date fields accordingly.
- Locate and select the specific invoice/quote and click its designated dropdown arrow.
- Click View activity.

- The transaction activity will show its status as Sent and display the receiver of the sent transaction.
On the other hand, you can also send yourself a copy of these transactions once you send them to your customers. This way, you can automatically check the full details of the invoices/quotes.
- Open your QBO account.
- Navigate to the Gear icon and select Account and settings.
- Select the Sales tab and click the dedicated Pencil icon for the Messages section.
- Tick the Email me a copy at option (sent to your Intuit account email). You can also utilize the Copy (Cc) or Blind Copy (Bcc) fields if you want to deliver it to another email address you may have.
- Once done, hit Save, then Done.

After receiving the copy, you can open it to review which individual the invoice/quote is for. Use these images below as a reference:
For invoices:

For estimates:

I'm also attaching an article that can help you modify the appearance and information of your sales transactions: Customize invoices, estimates, and sales receipts in QuickBooks Online.
Need more guidance or insights about your sent transactions in QuickBooks? Feel free to drop by again on this thread so we can assist you accordingly.