You can easily check for the latest published version of Cnotes by visiting https://compojoom.com and going to Downloads->CNotes.
Updating CNotes to the latest version is by no means different than installing the component! You do not have to uninstall the previous version; in fact, you are discouraged from doing so. Simply follow the installation instructions so as to install the latest CNotes version over the existing installation. That's all! All your settings are preserved.