The app won't allow me to save new sales receipts or invoices?

Hello macgyver-renovat,

Thanks for reaching out in the Community. I'll be happy to help so you can have a seamless experiencing while using the QuickBooks mobile app. 

In order to troubleshoot the issue you've described, could I have you try the steps below?: 

1. Change the Wifi data connection on your device to 4G (varies by device).
2. Close and restart the app.
3. Clear app data. To do this:
   1. Open your device Settings.
   2. select Apps (varies by device).
   3. Choose QuickBooks app from the list, then select Storage.
   4. Select clear data.
4. Power down and restart your device.
5. Uninstall and reinstall the app.

I recommend trying this and letting me know how you make out. I'll be one message away.