If you bought OS 3 recently, and it comes with firmware 2.1.7(2) or above, you can press B3+B2 (i.e. press and hole B3 then press B2, like how you do Ctrl+C) to reset the controller to WiFi AP mode. This will reset WiFi without erasing settings. Then you can go through the WiFi setup steps again to get it connected to a different WiFi.