Use the Transactions app to convert your transaction files to required by your accounting software file format.
This tutorial shows how to import an OFX file into Quickbooks Online.
Login into Quickbooks Online to import an OFX file and click on 'Banking'.
Then select an account you want to import your data into.
Look for the 'File Upload' button and click on it.
Look for the 'Browse' button and click on it.
Select an OFX file you created or you downloaded from your Bank. Then click 'Open' and 'Next'.
Review that OFX file you are going to import: filename, Account ID, Account Type, and Date range.
If everything matches as you expected, select Quickbooks account you want to import your data into. Then click 'Next'.
Then click 'Let's go!'.
Now your OFX file is imported. Click 'For Review'. The Payee name from the OFX file is shown under the Description column.
The Payee column is empty because it is Vendor records in Quickbooks. Some Vendor records will be automatically matched, some are not. This is a new account, there are no Vendor records yet, so nothing is matched.
Confirm the Category, which is expense or income account. Click 'Add' to add the transaction to the register. Continue for all transactions.
Let's say you realized, that it is an incorrect imported OFX file or something wrong with a file, and you don't want those transactions to be here. So, select all transactions.
Then select 'Batch actions' and click 'Exclude Selected'.
Go to 'Excluded'. Select all of them again.
Then select 'Batch actions' and click 'Delete'.
So, this way, you completely delete those transactions from Quickbooks Online.