How can I download my full ledger for my accountant?

You can run a General Ledger report, @usersochungtak.

To get your entire ledger, make sure to specify the Report period to All Dates to make sure the specific transactions appear, like when you started to get customer payments, made expenses, and more. This way, your accountant can extract the income statement, balance sheet, and other financial reports from the ledger. 

Let me show you how:

1. Sign in to your QuickBooks Online (QBO) account.
2. Click the Search icon on the upper right panel.
3. Type general on the search field and then select General Ledger.
   
4. From the Report period drop-down, choose All Dates and then click Run reports.
   
5. Click the Export icon to auto-download using Export Excel (.XLSX file) or Export to PDF (then click the Save as PDF button on the PDF window).
   
   

I've added a reference on how you can personalise reports in QBO to dig deeper into specific business data: Customise reports in QuickBooks Online.

Also, you can email this directly to your accountant by simply clicking the Email icon on the upper part of the General Ledger report.

I would expect a lot of questions coming. If you have one, please don't hesitate to comment them down to assist you further. I'm here at your service anytime. Have a great rest of the day!