For those who wishes to change the sudo cache timeout for a specific user, let’s userA
sudo visudo or (su - then visudo)
We have now set the sudo timeout “password-less” prompt to 20mn, to make it infinite set it to -1
If for some reasons you have it set it to 20 or -1 and wish to re-enable the password prompt, simple type sudo -K
** remember even after a reboot, the sudo cache would still persist if it is of course in its timeout grace time.