Left side and right should both have the button/switch, if you have the original motor that is, but I have seen cheap aftermarket that come without it though
It seems to be the same for a lot of Nissans/Infinitis of many years
on the back/bottom of the cover plate of the motor itself, there will be a tiny little rubber button that you can press, 5th gen it should be almost dead center of the door itself
I did take the entire panel off for easier access, there is no need to remove the clear plastic

1.(window is completely up) ignition OFF
2. turn key to power ON
3. hold button and 1-press (not auto) roll window all the way down
4. let go of button and again 1-press roll the window all the way up
5. turn ignition to OFF

and that's it it has been reset, you can now do the 2-press auto, worked on the first try for me (2001 i30t)
On 5th gen there is nothing hiding the button, other years/models may have an extra piece of plastic that is hiding it
screwdriver points at the button ! (on front right door in this example)