Setting lister up so that all listers show size of folders

I have added Size to one of the headings in my listers, but size not displayed. I had selected Folder options and then Options.
In the Options area I changed Get folder sizes to Automatic.
In Save format I then clicked Apply followed Save the current folder format.
This worked - I now saw folder size in the Size column of the lister.
Finally I selected Settings and clicked on Set as default Lister
When I selected a different folder Size was not displayed.
What have I missed?

Thank you Leo for your usual prompt and very helpful response.