What to do to safely test creation of Invoices? Can we disable the sending of invoices to customers while testing? If yes how can they be sent with the user interface?

Thanks for posting this to our care and sharing insights about holding and sending invoices, @paoloqbcaliforni.

I would love to share with you the steps on how to disable sending of invoices. However, this ability isn't available in QuickBooks Online (QBO) for now.

When you want to create test invoices, you'll want to click the Save button from the invoice window to save the transaction safely. I've added a screenshot below for visual reference.

When invoices are assured correct and it's time for you to send them, you can go to the customer transaction list and then click the Triangle button to send them individually.

Here's how:

1. Go to the Sales menu and then select Customers.
2. Choose the Transaction List tab.
3. Find the invoice you wanted to send, and then click the Triangle button ▼ beside Receive payment from the Action column.
4. Select Send and then hit Send.
   
   

You can also send the transactions in bulk from the Transaction List by checking the box of each transaction. Click the Batch actions button and then choose to Send transactions.

Additionally, you'll want to check the App Center or check the Google search engine to search for supported QuickBooks APIs, helping manage QuickBooks Online to control sending invoices.

Moreover, here's a list of articles to effectively track and record your sales transactions in QBO: Manage Customers and income.

If you need additional assistance about record-keeping sales and expenses, feel free to place a comment here. Anytime I can get back here to help. Have a great day ahead.