Click or scroll with the touchpad
You can click, double-click, drag, and scroll using only your touchpad, without separate hardware buttons. Access these features in the mouse and touchpad settings.
Click the icon at the very right of the top panel and select System Settings.
Click Mouse and Touchpad.
Switch to the Touchpad tab.
To click, double-click, and drag with your touchpad, select Enable mouse clicks with the touchpad. To click, tap on the touchpad. To double-click, tap twice. If your touchpad supports multi-finger taps, you can right-click by tapping with two fingers at once. To drag an item, double-tap but don't lift your finger after the second tap. Drag the item where you want it, then lift your finger to drop. You still need to use hardware buttons to right-click.
You can scroll using your touchpad using either the edges of the touchpad or using two fingers.
Select Edge scrolling under Scrolling to scroll using the edge of your touchpad. When this is selected, dragging your finger up and down along the right side of your touchpad will scroll vertically. If you also select Enable horizontal scrolling, dragging your finger left and right along the bottom of your touchpad will scroll horizontally.
Select Two-finger scrolling under Scrolling to scroll with two fingers. When this is selected, tapping and dragging with one finger will work as normal, but if you drag two fingers across any part of the touchpad, it will scroll instead. If you also select Enable horizontal scrolling, you can move your fingers left and right to scroll horizontally. Be careful to space your fingers a bit apart. If your fingers are too close together, they just look like one big finger to your touchpad.
Two-finger scrolling may not work on all touchpads.