NuiNet receives periodic updates. When an update is available, the version number link at the top right of the Admin page turns from green to orange and it is suffixed with "(Update Available)".
Clicking the version number link, takes you to the updates page where you can choose which version you want to install. You almost always want to install the latest version, as it contains all the updates and fixes of the previous versions combined. The only time it is advisable to download to an older release, is if the latest version is causing problems that you didn't previously have. If so, please report the problem to support.
Updates take several seconds and happen in the background. The page will not update when the install has completed. However, once finished, when you refresh another page, for example "Accounts", you will notice that the Version number has updated and is now green.