This has been frustrating me for a while every time I use midnight commander to edit a file the nano editor keeps appearing, I’ve been used to using vi since I first started using UNIX in the 90’s so its a bit like trying to teach an old dog new tricks. The problem is midnight commander uses the default editor for the session, unless you tell it to use the internal editor. Typically I would edit the bash.bashrc and add vim as editor in there.
However I have found out a better way by using
sudo update-alternatives --config editor
This will bring up a small menu with the editors you have installed, simply choose the one you wish to use.