You can export certain types of transaction from one file to another without using a third party application.
To do this you must meet the following criteria:
Step 1: Set preferences appropriately to allow the export.
Step 2: Create a Custom Transaction Detail report for each type of transaction you want to copy to the new company file.
Step 3: Export the report to Excel.
Step 4: Enter transactions into new company file using the Batch Enter Transactions screen.
If these steps do not resolve the issue, you can read discussions and post messages and questions relating to your issue on the Intuit QuickBooks Community site for free or you can contact a technical support agent for additional guidance. Fees may apply.