In order to switch from one node to a different one you can either disconnect from the node you are currently connected to and then choose a different node - from the right side menu or from the map - and click on it to connect, or you can directly click on the new node you want to connect and hit "yes". Now, the switching process will take 15 seconds, and the timer will be displayed for you to see. This second are precious for our server to know you have disconnected from one node and you are free to connect to a different one, so please give it the time :)