All changes that are done under the configuration tab is saved in a working copy, which is stored in your current browser session. This enables you to make multiple changes before you deploy it as your running configuration. You can also use live staging to test your new configuration or e.g. compare the working copy with another revision.
To deploy your working copy, go to Configuration -> Deploy working copy and enter a message, then click on the deploy button and after that it will be automatically pushed to all the other nodes in your cluster.