Why does opening a second window close the quickbooks app?

Thanks for bringing this concern to our attention here in the Community, accounts446.  

I understand it's annoying to close your QB App every time you open another window. I have some troubleshooting steps for you to try to see if you're able to sustain the app even opening the second window.  

The first place to start is by clearing the app's cache. There are a couple of options for this, and I recommend the Reset app data option through the uppermost Help menu. This doesn't impact your data that's been entered into your books but gives the app a good scrub to remove temporary files that could be causing problems. 

If the error persists, I invite you to reach out to our support team outside of the Community. This will give an agent the opportunity to privately collect your account information and help you rectify the issue. 

You can always get back here if you have other concerns or questions about accessing your QBO account. I'll be here to help you. Stay safe.​​​​​​​