External windows mouse invert scroll except touchpad
I've had a simular issue as an inverted (external) mouse is pretty... annoying.
If you never use another computer, you will get used to it eventually.

But if you would like to customize buttons, I would recommend you steermouse as per their site:


  SteerMouse is a mouse driver that lets you freely customize buttons,
  wheels and cursor speed. Both USB and Bluetooth mice are supported, no
  matter whether the mouse is designed for Windows or Mac.