Hello, I would like to set up my POS 80mm printer so that it automatically prints a receipt when I complete a sales invoice. What steps should I follow?

Connecting your POS system to QuickBooks has been discontinued, Louz. You'll need to use third-party applications to achieve this.

Follow these steps to check out some apps that work well with the program.

1. Go to the Apps menu. 
2. Choose the Find apps tab. 
3. Select the application that suits your preferences.
4. Click Get app now.

Also, we can manually record the transactions created within the POS system to QuickBooks Online (QBO).

You can also manually upload your transactions in QBO using the CSV file.

I'll be on the lookout for your reply if you still have concerns regarding integrations with QBO.