An I able to change a batch of invoices to unpaid without having to do each one at a time?

Welcome to the Community, @jransamy.

Batch action for changing paid invoices to unpaid is unavailable in QuickBooks Online. Batch action allows you to print, email, and enter transactions in bulk. 

In the meantime, we'll need to open each invoice to mark it as unpaid. 

Here's how:

1. Go to the Sales menu and select Invoices.
2. Open the Invoice you want to mark as unpaid.
3. Click the Payment made hyperlink in the upper right corner.
4. Choose the date you marked it as paid.
5. On the Receive Payment page, click the Clear Payment button.
6. Once done, click Save and new.

Should you need to edit your invoices, feel free to check out this article: Edit multiple invoices at the same time in QuickBooks Online.

Let me know if you have anything else to add. I'd be glad to assist you as soon as I can. Have a great day.