Follow the procedure described in the topic https://www.odoo.com/forum/Help-1/question/How-can-I-transfer-my-fiscal-years-balances-to-my-new-financial-year-54378 until Step 5.

6. Create a Purchase and/or Sales Journal for Outstanding Entries

We recommend you to create separate purchase and sales journals to post the outstanding entries (both invoices and credit notes) from your previous accounting system. This will allow you to easily keep track of your open invoices and credit notes. Of course, you can also post oustanding entries in a Miscellaneous journal.

Go to the menu Accounting > Configuration > Journals > Journals.

Create a new purchase and sales journal to post your outstanding entries. Make sure to respect the following settings:

• Type should be Purchase, Purchase Refund, Sale or Sale Refund.
• The Entry Sequence will be created automatically on save.

Now you can start entering your outstanding customer and supplier entries according to your list of open entries at the end of the year.

Go to the menu Accounting > Customers > Customer Invoices to post your outstanding sales invoices. Go to the menu Accounting > Customers > Customer Refunds to post your outstanding sales credit notes. To post your outstanding purchase invoices, go to the menu Accounting > Suppliers > Supplier Invoices. To post your outstanding purchase credit notes, go to the menu Accounting > Suppliers > Supplier Refunds.

We recommend you to use suspense accounts instead of expense or income accounts. Indeed, your expense and income accounts have already been posted in the previous financial year, and there is no need to transfer these balances. The outstanding entries from previous financial years should not contain any VAT entries; they only get the balance the customer still has to pay you, or the balance you have to pay to the supplier.

7. Enter the Opening Balance (Opening Entry)

For each account that needs to be reopened, enter account data (debit or credit) in the journal. For this operation, go to the menu Accounting > Journal Entries > Journal Entries, click the Create button and select an opening journal and the opening period.

You can also use Odoo's generic import tool if you load the balance of each of your accounts from other accounting software.