I am running a trial balance for the whole tax year but report only shows the sales for the last month of the tax year not the sales for the whole tax year

Thanks for joining us here in the Community, @accounts-chelete. 

The Trial Balance report is designed to show all running balances of the accounts. Thus, changing the date range of the reporting period to a monthly basis won't change the running balances.

As an alternative, you can consider pulling up and customizing the Profit and Loss and Balance Sheet report. This way, you'll be able to see the revenue or expense of each account within a specific period. Here's how:

1. From the left menu, click Reports.
2. Search for Profit and Loss or Balance Sheet.
3. In the Report period section, select the specific month you want to show.
4. Click Run report.

I've got you an article for more details: Customize your Reports in QuickBooks Online.

Let me share the following articles for future reference. These resources provide an overview of how to tailor the information displayed on reports. From there, you’ll see the complete list of reports included in your subscription.

• Reports included in your QuickBooks Online subscription
• Customize reports

Click the Reply button if you have other concerns or questions. I’ll get back to answer them for you. Enjoy the rest of the day.