will be closing my account, can I get a complete backup of all my transactions detail (estimates and invoices)

If you’re using QuickBooks Online Advanced, there’s a built-in Backup feature that makes it easy to save all your data, Sergio.

You can access this feature directly in your account to ensure your information is securely saved before closing your account.

If you don’t have the Advanced version, you can still save your data using the Export feature to download your Reports and Lists into Excel.

1. Go to Gear Icon > Export Data.
   
   
2. In the Reports tab, choose which reports and lists you want to export.
3. Click Export to Excel.
   
   

You can check this article to learn more about how to export other data from QuickBooks Online: Export your data from QuickBooks.

Let us know if you have any further questions in the comments, and we'll be happy to help you.