While entering expenses on my Iphone - account required section looks empty however all accounts predefined and I am able to see on laptop but not appears in phone

Welcome to the QuickBooks Community!

Let's perform some troubleshooting steps to get your issue resolved.

It's possible that the QuickBooks mobile app on your iPhone had a data issue, that's why the accounts in the Account required section aren't showing. To verify, let's reset the app's data. Here's how:

1. Go to your iPhone's Settings menu, select Accessibility (varies by device), and click Apps.
2. Select QuickBooks from the drop-down and choose the Menu tab. 
3. Select Help & Feedback.
4. Click the Refresh data or Reset App Data.
5. Reboot the app. 

Once done, check if the accounts already showing in the Account required section when creating an expense transaction.

If you get the same result, I'd recommend uninstalling and reinstalling the app for a clean slate. You do not need to worry since it won't delete any of your app's transactions. 

Just in case you want to learn more about using the QuickBooks mobile app, you can watch this video tutorial for more guidance: How to Use the QuickBooks Mobile App.

Come back to this post if you have other concerns or follow-up questions about this. I'll be around to provide further assistance.