Are you sure they are Sonos One speakers?  If so, they are not Bluetooth capable.  The only direct connection available from an iPhone to Sonos One is Airplay. 

They are Sonos 1 and you are 100% right. After 3 hours of playing with them, I switched to Airplay and the sound is great.

I am certainly a VERY senior citizen, but I thank you for giving me the right answer quickly.

ps. this is the first time I have ever used, or understood airplay.

DD

Just so you’re aware, for future questions, there is no Sonos 1 speaker. There are the Sonos PLAY:1s and the Sonos Ones. Helps folks interpret and come up with a true answer. ;)

And yes, that name difference is much more minor than the difference in the actual speakers. But we have to live with Sonos’ marketing choices, as difficult for this community as they may be.