For instance, to right-click method on touchpads without a physical button you need to perform a two-finger click (just tap anywhere with two fingers). Clicking in the bottom right area of the touchpad no longer works.
If you don’t like this behaviour — and there’s a fair chance you might not — you can use the Tweaks app (see step #5) to change the setting.
Fonte: OMG Ubuntu ( veja o link para saber como corrigi-lo)