I’ve had a problem with several invoices that my customers paid online, but the invoice still says overdue. Is this just a horrible glitch?

Hello there, conleyspest.

When a user encounters unexpected behavior, we can perform basic browser troubleshooting to fix the issue. It could be that the stored cache or an outdated browser is the reason why invoices show as overdue status.

We can start by opening a private window and use it to access QBO:

• Google Chrome: Ctrl + Shift + N
• Microsoft Edge: Ctrl + Shift + P
• Firefox: Ctrl + Shift + P
• Safari: Command + Shift + N

Once done, let's try to double-check and verify if the transactions are still showing overdue or not. If it's working fine, we'll have to go back to your regular browser and clear the cache to eliminate the junk files. If you still encounter the same issue, you can use other supported browsers. 

If it persists, we can manually mark the invoices as paid. Here's how:

1. Go to Sales on the left panel.
2. Within the Customers tab, locate the invoice.
3. Click Receive payment under the Action column.
4. Then, enter the paid amount of the invoice.

Here's an article that will you when modifying sales forms: Learn how to personalize your sales forms. 

Stay in touch if you have other questions. I'm always around to assist you further. Take care and stay safe!