If you’ve set up two separate Sonos households, you’ll need to go back and factory reset one of them. Then reconnect your controller to the one you didn’t touch, and use the ‘add a device’ feature, rather than the ‘set up a new system’. This will get all your Sonos devices in the same Sonos system, and allow them to talk to each other. Once they’re added back to the single system, you can then ‘bond’ them as surrounds, if that is desired.

Some minor considerations, mostly for others reading this thread: you can never mix S1 and S2 systems. Also, you normally should never factory reset a device, unless instructed to, as it rarely ‘fixes’ anything, but instead hides the issues, and deletes any data that Sonos might be able to use to assist you. 

When I uninstalled the sonos app (android) & re added it, this is what I get. I don't want 2 systems? 

Moderator edit: removed serial numbers from pictures

I want the speaker on System 2 to be on System 1???

So why not follow the advice you’ve already been given? 

@nik9669a, I didn't set up 2 systems. Not too sure why you have to respond in that manner? I'm asking for help, not sarcastic comments.

Hope you have a fantastic Saturday night  

Your first post said “one is working the other is now on another system”. So, you set up 2 systems by mistake. In his reply, Bruce explained what to do: “you’ll need to go back and factory reset one of them. Then reconnect your controller to the one you didn’t touch, and use the ‘add a device’ feature, rather than the ‘set up a new system’. This will get all your Sonos devices in the same Sonos system, and allow them to talk to each other.” You’ve evidently not done that, or not said that advice didn’t work. 

@nik9669a , I've done this numerous times, every time I follow those steps it keeps showing 2 systems.

Try this:

Power down all speakers except the one in a system on its own. Factory reset that one, then power it down. Power down your router. Wait a few minutes, then restart the router. When it’s fully restarted and wifi is running, restart the Beam, then the “other” One. Then power the reset One and add it to the existing system. 

Check the serial number of the unit that you Factory Reset.