I’m not sure what you are suggesting. Are you suggesting I buy another phone?
The issue is with the Sonos app on the Macbook. The Deezer app connects on both the iPhone and the MacBook. So the fault seems to be with the Sonos app on the MacBook, as Deezer works on other apps. Strangely, the Sonos app on my iPhone does allow me to connect Deezer to the app. But when I’m on the laptop I should be able to use my MacBook to open Sonos and launch Deezer. How do I get it to work with Deezer on the desktop app? The password is obviously correct or it wouldn’t work elsewhere.
You only need to setup a music service once (per music service account) per Sonos Household (HH) using any Sonos controller App on the Network.
The service/settings for the music service are stored on the Sonos speakers/devices in the HH and should be viewable from any/every controller attached to the same HH. Try (fully) closing and reopening a controller App if it’s out of sync and if still no joy there, consider resetting the controller App and re-connecting it back to the EXISTING Sonos Household.