how do i change search engine for siri on apple watch

How do I change the search engine for Siri on the apple watch and iPhone.

I have tried to change the search engine to google for Safari on the phone but if I ask Siri "show me a picture of a donkey"

the watch and phone both clearly shows Bing is the search engine when pictures are displayed.

However double checking the settings - search engine shows google.

Regards

Lars