Raspberry Pi, Ubuntu 20.04 server. Make sudo require a password

I have installed Ubuntu 20.04 server image on a Raspberry Pi 4. As per standard install there is no password requirement for sudo, this is something I most definitely want to change. I have tried already running:

sudo visudo /etc/sudoers.d/010_pi-nopasswd

and entering into it:

ubuntu ALL=(ALL) PASSWD: ALL

All to no avail.

Please can anyone help?

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