Since the app update I can no longer locate the bit of the app to send invoices or see what ones still need paying

I can help you with resolving the error you're having with your invoices while using the mobile app, samsonselec.

The error you're having can be caused by the piled-up cache in your application. To resolve this, you can clear the app's cache, which is a temporary storage area that stores frequently used data to speed up the app's loading process. Clearing the cache can free up space, improve the app's performance, and resolve issues within the app. 

Here's how to clear the app cache on your iPhone:

1. Tap on the Settings icon and then choose General.
2. Click on iPhone Storage and choose the QuickBooks Online (QBO) app.
3. Tap on Offload App to remove the app and its data temporarily or tap on Delete App to remove the app and all its data permanently. 

For Android: 

1. Open your phone's Settings.
2. Look for the QBO app.
3. Tap the clear data or the clear cache option.

Once you're done, log in to your account and verify if you are now able to create, send, and check any open invoices without any issues. 

If you are encountering any errors while using the mobile application, you may refer to this article on how to resolve common errors: Common Errors in the Mobile App.

In case you receive an invoice payment from your customers, we have provided a detailed guide on how to record it using the QuickBooks Online mobile app. You can find it here: Receive an invoice payment using the QuickBooks Online mobile app.

I'm always here if you need more help with your invoices. Just let me know by leaving a reply below. Have a great rest of the day!