How to update npm

I'm trying to install mean.io boilerplate. It fails when running `sudo npm install -g meanio@latest`. Prior to failing it notes that it 'wants' npm version 1.4.x, whereas I have 1.2.18 installed. So I tried updating npm to the latest; several ways. Last of which was... ubuntu@ip-xxx-xx-xx-xxx:~$ sudo npm install -g npm /usr/local/bin/npm -> /usr/local/lib/node_modules/npm/bin/npm-cli.js npm@1.4.7 /usr/local/lib/node_modules/npm ubuntu@ip-xxx-xx-xx-xxx:~$ npm --version 1.2.18 Why is it still showing version 1.2.18, when I just updated to 1.4.7?