Naplioprie89 You need to go to the WebGUI of your router, how to do is explained here:
Log in to the internetbox.home web portal - Help | Swisscom
the router password you can find in MySwisscom -> Your Products -> Internet -> Your router; and there (see picture):

Once in WebGUI, activate "Expert Mode" and then WLAN -> Settings, there you can switch between the channels