I create an invoice and send it to the customer, it automatically come up paid before I’ve sent the invoice

Good day, isecuresolutions. 

I can help correct the invoice that was marked as paid in QuickBooks Online (QBO).

A newly-created invoice will be marked as paid if you have turned on the Automatically apply credits feature. This feature will automatically apply payments to the new invoice and mark it as paid if your customer has a credit balance.

Here's how you can check: 

1. Click the Gear icon, and then Account and Settings.
2. Go to the Advanced tab.
3. Click the pencil (edit) icon on the Automation section.
4. Deselect the Automatically apply credits box.
5. Click Save, and then Done.

Once done, let's open the created invoice that was marked as paid and delete the applied payment. This way, it'll mark the invoice as unpaid.

1. Click Sales from the left menu, then find the newly-created invoice.
2. Select the 1 payment link in the upper right hand above the PAID payment status.
3. Hit the date link.
4. On the Receive Payment page, select the invoice.
5. Click More at the bottom and select Delete, then choose Yes to confirm.

After that, you can resend the invoice to your customer. 

I'm adding this article to learn more about receiving payments and applying for credits in QuickBooks Online:

• Record invoice payments in QuickBooks Online
• Handle a customer credit or overpayment in QuickBooks Online

That should do it. Let me know if you have any other questions about the invoice status sent to your customers. I'll be happy to help you out.