Update sklearn

For the code I want to write I need to use at least scikit-learn version 0.19 but 0.18 is the version currently installed. When I tried to install sklearn on bash to get the new update I was denied access. How should I get access to the newest version of sklearn?

This help page explains how to install new modules; if you add "--upgrade" to the command line, then you can use the same techniques to upgrade them.