What happens to open invoices when you make an customer account inactive?

Yes, bravolock. The system automatically generated the adjusting data because you've made a customer inactive who has an outstanding invoice. Allow me to lay out more details about this.

QuickBooks creates these transactions (payment and credit memo) to clear off the existing balance. This process makes the invoice marked as Paid. It helps you avoid discrepancies in your records in the program.

You may leave those data as it is or handle it by activating the customer momentarily to clear it off as bad debt. You may take this procedure to settle an amount the customer owes that will never get paid.

If you decide to write it off, let's activate the customer first and delete the QuickBooks-generated adjustments:

1. Go to the Sales menu and select Customers.
2. Choose the inactivated customer's profile and tick the Make active button.
3. Navigate to the Transaction List tab and click Edit under the Action column for the Payment and Credit Memo.
4. Click More and then Delete.
5. Once prompted, hit Delete to confirm the action.

Following that, please proceed with writing off the balance. To completely guide you with the process, please review and follow the steps provided on this link: Write off bad debt in QuickBooks Online.

I'm also adding this article about generating customer statements: Create and send customer statements in QuickBooks Online. It could help you enter and send complete customer summaries for their invoices, payments, and credits. You may also utilize it to notify them of their upcoming overdue balances towards you.

I'm just around the corner and always available to provide additional help. Whenever you have more concerns with your customer and their invoices or other transactions, please add a comment on this thread. Take care.