Here is how to adjust mouse speeds on a Chromebook
1. Log into your Chromebook.
2. On the bottom right of the screen you will see the time (also called the notification area). Click on that.
3. Click on "settings"
4. Look for "Devices". There will be a slider that controls the Mouse speed. All the way to the right will be "Fast". All the way to the left will be "Slow"