Hi robertp
These buttons are hidden by default intentionally.
In order to show them, you have to click on the specific order item(s) you want to change the stock. Once the order item(s) are selected (they will be coloured in red), the buttons will display automatically.
And that error you are getting is normal because you tried to change the stock without selecting the order items first, so ATUM can't know which item should be used here.
Best Regards,
Salva.