Ubuntu 14.04 touchpad scrolling

In general, the touchpad on laptops can support scrolling by touching the left side or bottom of it if appropriate driver is installed. For Ubuntu 14.04, it sets touchpad to support two finger scroll by default. If one tries to use one finger scroll, follow the steps below.
1. Open System Settings->Mouse&Touchpad.

2. Unlock the Two finger scroll.

One can also set up Natural scrolling by this way.