Row Content - Item Details Container
The Item Details row element, by default, does not have a "Focus Item" when inserted.
Edit Item Details Container
Clicking on the Focused Item "Configure" button will open the "Select Item" window.
Start typing a reference to the item you want to insert into the "Item Details Container". Clicking on the item from the auto-complete drop-down results and then clicking the "Save" button will insert the item into the container.
Clicking on the inserted item will then provide access to the Item Details element.
The toggle option for Show item# is here and controls the display of the item# and item description.
The Item Details element is found as a sub-component of the Item Details Container.
Also see Common Element Actions for more details on managing the Item Details Container.