In my Murano I have the [overly expensive] ipod adapter kit that ties in with the sat radio device. I've found a few tricks, might help if the Leaf is designed the same way.
I've noticed that if you don't have anything already queued up on the ipod, then yes, it starts at the first track on the entire device. But if you have a playlist already selected, it will continue playing wherever it left off.
The one really annoying issue is that if you have your ipod on shuffle, when you connect it to the system it switches back to non-shuffle. EVERY TIME you connect it, or every time you restart the vehicle. As a work-around, I have found that it plays in the order of the playlist as it was displayed in iTunes when the iPod did its last sync. So, before you sync your ipod, make sure your playlist is shuffled, and sort by the "Play Order" (first column on the playlist). Then sync your ipod, start playing the first listed song on that playlist, THEN connect it to the vehicle. Now just don't touch, you'll be playing your "pre-randomized" playlist. Once I had that set up, all I ever use is the forward/backwards track buttons.
AGAIN, this is for my MURANO, not sure if the Leaf behaves the same way. Would be nice if someone could try it out and report back to see if it's the case.
2017 Nissan LEAF SV