Hi there, @MIMAC.

I appreciate you joining us here in the Community today. I'm here to share some insights about collapsing and expanding an account for Balance Sheet in QuickBooks Online. 

Currently, the ability to collapse and expand an account on the Balance Sheet report is currently unavailable in QuickBooks for Mac. This is only applicable to the Windows version. To learn more about customizing a company and financial reports in QuickBooks, you can check out this article: Customize company and financial reports.

I can see how this option would be beneficial to you and your business. I'll send this feedback on your behalf straight to our developers. This way they'll be able to determine features that needs to be added in future updates. Doing this will also help them understand how we can improve your QuickBooks experience. 

Please know that the Community is always here to help if you have any concerns with QuickBooks. Wishing you and your business continued success.