Invoices

Yes. If the invoice has been paid, register the transaction as a sales receipt.

It's nice to see you posting in the Community forum, @MaryG0.

Yes, invoices created in different invoicing programs should be entered so that QuickBooks Online (an accounting program) can track them.

To do this, you can manually import the invoices or link the invoicing software. Let me guide you how:

To import invoices into QuickBooks Online (QBO):

1. Go to gear icon at the top.
2. Select Import data.
3. Choose Invoices.
4. (Optional) Select the checkbox to add new customers that don't already exist in QuickBooks.
5. Select Browse and then find and select the spreadsheet of your invoices.
6. Select Next and follow the onscreen instructions.

To look for an app and link it to QBO, here's how:

1. On your QBO account, click Apps in the left menu. 
2. Go to the Finds Apps tab.
3. In the search tab, type in the app you're looking for.

For future reference, check out this article to learn how to receive invoice payments in QuickBooks Online. 

Additionally, I'm attaching our Community link if you need help adding, organizing, and sending invoices: Invoices and payments.

It's nice working with you, @MaryG0. Please know that I'm just a reply away if you need any further assistance managing transactions in QBO.

Thank you for your input, but I had tried that already and was not able to do it. I get the following message, "Import invoices isn't quite ready to support sales tax", it also says they are working on it. I guess the other thing would be to add them manually?? But what about the ones that have been paid??

 "But what about the ones that have been paid??"

@MaryG0 

See the first response, by Fiat Lux - ASIA 

I can share some information about invoices, @MaryG0. 

For the amounts that has been paid, you can create a sales receipt. The difference is that invoices are issued before a business has received payment from a customer, and a sales receipt is issued after payment has been collected.

Here's how to create and send sales receipts in QuickBooks Online if it has been paid on the spot. If it'll be paid later, create invoices in QuickBooks Online. 

If you need to personalize and provide additional information to your invoices, estimates, and sales receipts, here's how to customize invoices, estimates, and sales receipts in QuickBooks Online. 

I'm always here if you need more help adding your invoices. Let me know in the Reply section. Keep safe, and have a wonderful day!

@MaryG0 

Prepare your invoice data with the following template

then use an importer tool to proceed

https://get.transactionpro.com/qbo

You may consider having a backup restore app to lower any risks

https://partnerwithus.rewind.com/quickbooks