On Ubuntu, the default for Right-click on the trackpad is two fingers.
To change this to clicking the right side of the trackpad, follow this guide.
1 Install GNOME Tweaks
Open the GNOME Launcher and click on Ubuntu Software. Search for and install 'GNOME Tweaks'.
For further information on 'GNOME Tweaks Tool' see our guide here.
2 Launch 'GNOME Tweaks'
Click on 'Launch'
3 Keyboard & Mouse
Navigate to the 'Keyboard & Mouse' settings tab.
4 Mouse Click Emulation
Under 'Mouse Click Emulation', simply click and enable the second option: