New Sonos app

Maybe see if this link will perhaps assist you…

https://support.sonos.com/en-us/article/connect-sonos-to-a-new-router-or-wi-fi-network

Delete and reload your App as something is wrong there, corruption or an older version.

Once you have done that, click the “system settings” the gear icon you should get the system settings page.

Once it opens you should see a “Manage” on the right side, touching that will open the manage settings. It is of course par for this new app that the Manage looks like a text label and not a menu selector, but it actually is. I find I have to scroll the page up a bit too, in the default position it opens to the manage is apparently too close to other items and won’t select.

Once you get there you can then scroll down to Manage Networks and hopefully make your changes.