The Arc creates a dedicated 5Ghz wifi link to the surrounds, by the way, so if you’ve got them set up on your 2.4ghz wifi they may not be properly added as surrounds. Are they in the same Sonos room as the Arc, or a stereo pair in a different room?
Everything is in the same roome, including the router
In Sonos terminology, a “room” is used as a label to identify a speaker or collection of speakers. So your roomname could be Lounge or Mavis. Logically, the name relates to the physical space such as Kitchen or Study.
With a surround system, you (again in Sonos terminology) “bond” the surrounds to the soundbar. Let’s say that room in your house is your lounge, but let’s label it in the Sonos system as Fred. In your situation, the room called Fred should consist of Arc and two surround speakers (your profile says Play:1’s?). All of the speakers will physically be in your lounge for obvious reasons.
When you stream music from a source such as Amazon Music, Pandora, etc to Fred the music should automatically play through all speakers. Which speakers will produce sound from a tv signal - even if it’s a music program - will depend on the format of the signal, but it may only be the front speakers (your Arc) that play. The fact that streamed music only plays from the Arc suggests the surrounds aren’t actually set up as surrounds, but are either not yet allocated to a room, set as a different room, or have been added to a different system.
Which version of the app are you using, so we can try to guide you through checking your setup, if you need that help?
