All of the sudden several invoices previously paid are showing unpaid and overdue? What do I do? I dont want to mark them paid a second time and screw up figures

Welcome, @jboehmer. Glad to have you here.

Let's check your customer's profile to make sure both the invoices and payments are under their profile. Here's how:

1. On the left menu, choose Sales, then Customers.
2. Find the customer associated with one of the invoices showing unpaid, then click their name to open their profile.
3. Using the Transaction List tab in their profile, look for payments that have a status of Unapplied.

If you're able to find a payment that isn't associated with an invoice and should be, here's how you can link it:

1. Click on the payment to open it.
2. Under the Outstanding Transactions section, tick the checkbox next to the invoices the payment applies to.
3. Click Save and close.

That's it! For more information on receiving payments, I recommend checking out: Record invoice payments in QuickBooks Online

Keep me up-to-date here by using the Reply option below. I'm here to ensure your continued success. Have a good one!