I can help you correct the date of the write-off, @Meron GG.

When writing off, QuickBooks will use the date of the transaction that you used to zero out the invoice. For example, if you use a credit memo as a payment to close out the invoice, make sure that both the credit memo and payment is dated 2019 instead of 2018.

If the transaction didn't reflect accordingly to payment date. You can go back the paid invoice and click payment made to check if the payment is applied to the correct date.

If there's anything else I can do for you, please let me know. I'll be around to help you.