Hi, vicky34. I see you're following this thread and wanted to know how to write off customer invoices if your bank account isn't linked to QuickBooks Online.

When invoices sent through QuickBooks become uncollectible, you need to record them as a bad debt and write off them off. This keeps your accounts receivable and net income up to date.  

Thus, if your account isn't linked to Online Banking, you'll have to manually track each invoice by following the detailed steps in this article: Write off bad debt in QuickBooks Online.

If you need to address multiple transactions, you can do so by creating a journal entry. However, I suggest consulting with an accountant before making those entries. They can also advise you on alternative methods of dealing with uncollectible invoices.

Let me know if you still have other concerns or any follow-up questions about invoices. I'll be here to help.