Whatever we want to call that side column... I think it would be better if it was consistent page to page. It never has been since the day I installed.
There is no widget "sidebar" (right) option for the What's New page.
And there's no widget "sidenav" (left) option for the Forums List page.
In other words... the side column (nav / bar) are on opposite sides for each of those pages. It does not appear I can line everything up (in the side column) on the same side for both pages.
Have you looked at the admin cp page for widgets? admin.php?widgets/
There you can configure each widget's position.
But keep in mind, that a real sidenav (like the one on https://xenforo.com/community/account/ on the left side) is not a widget and not easily be removed or moved to another place.