Atom editor: How to jump back and forward

I think you are looking for the package "last-cursor-position":

https://atom.io/packages/last-cursor-position

If you want to modify the key binding, click on "view code" for the package and edit the file keymaps\last-cursor-position.cson

Edit: Or better, override keybindings in your keymap.cson

An extra step for those who got used to toolbars in IDEs: to add "back" and "forward" actions to toolbar, I've installed these two packages in addition to last-cursor-position mentioned above:

• https://atom.io/packages/tool-bar
• https://atom.io/packages/flex-tool-bar

Then edited the tool bar (there is a gear button on default flex toolbar for this) by adding two buttons that refer to last-cursor-position shortcuts:

{
  type: "button"
  icon: "arrow-left"
  callback: "last-cursor-position:previous"
  tooltip: "Back"
}
{
  type: "button"
  icon: "arrow-right"
  callback: "last-cursor-position:next"
  tooltip: "Forward"
}

Got this toolbar