I can no longer add bank accounts or review transactions in the mobile app?

Let's perform some steps to help fix the issue, CLCans.

You'll want to clear the cache app data on your phone to refresh it. To do this, you can follow the steps below:

For iOS devices: 

1. Click the burger icon (3 horizontal lines) at the bottom right.
2. Scroll down and select Help & Feedback.
3. Click on Refresh data.

For Android devices: 

1. Click the three-dot button at the top-right corner.
2. Choose Settings.
3. Scroll down and click Refresh data.
4. Select Yes.

If it doesn't help, you can uninstall and reinstall the app. 

You'll want to check the QuickBooks Online Mobile app FAQ. Learn where to find and manage the app.

Feel free to let us know if you need additional assistance in adding a bank account. Please know, we're here to help you always.