How do I look at the detail of previous tax returns?

Welcome to the Community, @info1218.

You're referring to your previous sales tax returns, correct? If so, you can go to the Sales Tax page in QuickBooks Online (QBO) to see the details. This can be done in two easy steps.

Here's how:

1. In QBO, go to the Taxes menu at the left pane to get to the Sales Tax page.
2. Click the History option at the top right or the Look at past returns in the Shortcuts section. 

Just in case, I'll add this article for future reference: File your sales tax return and record tax payment in QuickBooks Online.

Please know that I'm only a post away if you have any other questions or concerns. I'll be here to answer them. Have an amazing rest of the day!