Hi RidgelineLaw,
The custom field feature which you speak about is only available on Quickbooks Advanced which is a US only subscription not available to Australian users for the time being.
The photo in the link you have provided is of a US subscription of Quickbooks Online.
If this is something you would like to see in the future, I would urge you to provide this feedback within the product itself by going to Settings (cogwheel) > Feedback.
I hope this clears things up for you.
Kristian.
