How to record loss from previous year manually?

I want to make sure your books are accurate, @ksenia1,

QuickBooks calculates gains and losses based on the transactions recorded in the register. At the end of the year, the system zeroes out your income and expenses the uses a transfer called electronic swap to move money to Retained Earnings. If you need to enter adjustments from the previous year's data to record a loss, you'll need to add them manually.

After doing so, undo the previous reconciliation. Follow the steps below:

1. Click the Gear icon.
2. Tap Chart of Accounts.
3. Find the account you want to review.
4. From the Action column, click View register.
5. From the reconcile status column (indicated by a check mark), click the box multiple times to update the codes on the transaction:
   • C - Cleared
   • R - Reconciled
   • Blank - Not cleared or reconciled
6. Click Save.

7.  

   Here's how it looks like in QBO:

    

   

You can also find these steps from this article: How to unreconcile a transaction or undo a reconciliation.

Additionally, if you're using a QuickBooks Online Accountant (QBOA) version, you have the option to undo a reconciliation. Here's how:

1. Go to the Gear icon at the top and pick Reconcile under Tools column.
2. On the Reconcile an account page, select History by account.
3. On the History by account page, click the Account and Report period to locate the reconciliation to undo.
4. Choose Undo on the Action column, then Yes.
5. In the final confirmation window, pick Undo and OK.

Now you can proceed to reconcile last year's data with the corrections.

Please update me if you have any questions with the steps or need further assistance. I'll be available to help any time.