Connect/share info with Trello.

Welcome to the Community, Jason. Allow me to guide you in connecting third-party applications in QuickBooks Online (QBO). 

 First off, you may contact Trello and see if they support QBO. If so, here's how: 

1. In your QBO account.
2. In the left panel, click Apps and select Find apps.
3. In the search box, type "Trello" and look for the specific app. 
4. Choose the Get app now.  

If you weren't able to search the Trello app, that means it isn't supported yet. This said, I recommend contacting Trello to confirm if their software integrates with QBO. 

Furthermore, you'll want to check this article to learn how to disconnect an app and change your subscription in QBO. 

Feel free to reply if you need additional assistance connecting third-party applications in QBO. I'll be here to help. Take care.