Comment 2 for bug 1210575

There are two keys showing a pointer arrow pointing to the left on the Onboard layout. The key with only the pointer is to show and hide the click buttons. The key with a small clock (disk) on its left is to enable and disable automatic click. The automatic click is an accessibility feature that performs automatically a click each time the pointer stops moving.

If the automatic click is enabled, Onboard does not replace a manual left click with a right click. In this case, the click conversion only acts on automatic clicks. Since you are using a touch screen, you should keep the automatic click disabled.

If you get right clicks after holding your finger for a small lapse of time motionless on the touch screen, you might have the Simulated Secondary Click running. You can find the option to enable and disable the Simulated Secondary Click in the Universal Access panel of the System Preferences of Ubuntu.