HI,
can you please share a few screenshots with what you mean exactly. I do not see any of the options you are mentioning in the checkout field editor.
What I have found that at least come close to your tutorial was opening the backend of the checkout page, use the woocommerce checkout block
Then I open Options – Preferences where under General tab under Advanced section I activate custom fields.
Now at least I have an option to enter a custom field. However adding _billing_eu_vat_number is not possible as it asks to provide a custom field value. I have tried values ON, TRUE and some others but nothing works.
Here are my screenshots
https://ibb.co/drtnfdJ
https://ibb.co/BV0Q0LM
Can you please share a few screenshot with a proper tutorial on how to activate this?
Thank you.
Kind regards
Michal