You need to group the speakers on the grouping screen to play them together. You just tick the two rooms/speakers you wish to group and Sonos does the rest. 
(To open the grouping screen, tap the icon at the bottom of the now playing screen - the icon is a small picture of two speakers in front of each other.)

Thanks Ronny, they are already grouped and are playing . But with a kind of echo

Just checking - did you add the surrounds to the soundbar, rather than grouping them with the soundbar? ie. you tapped Add Surrounds and followed the instructions? 

Sorround has worked for years and are not echoing  ..