I’m sure when using a mouse in a text terminal the visual mode of vi/vim is useful, but I can never figure it out. In fact it prevents me from copying from a vi terminal in a window.

To temporarily disable mouse visual mode in a window, so you can copy your text it’s as simple as hold the SHIFT key down whilst selecting text with your mouse. Or you can disable it in that vi session by typing :set mouse-=a

To permanently disable visual mode in your session create or add the following to your ~/.vimrc file

set mouse-=a

If you need to do this for whilst using vi/vim under sudo, you’ll have to add the above into /root/.vimrc.