If your pointer moves too fast or slow when you move your mouse or use your touchpad, you can adjust the pointer speed for these devices.
Type "Settings" into the global search bar on your desktop. Click on the resulting Settings icon, or press Enter, to open.
Click on Mouse & Touchpad.
Adjust the Pointer Speed slider until the pointer motion is comfortable for you. You will see one slider per each pointing device, such as mouse or touchpad.
The Touchpad section only appears if your system has a touchpad, while the Mouse section is only visible when a mouse is plugged in.