Frontend / show the webp image

Hello,
actually 950 pictures have been optimized but in backend if i click on a optimize picture i still see the jpg and not the webp image and in frontend also the jpg.
So how i can display the webp image because by the settings of the plugins i checked “create webp version of images” and “display images in webP format on the site”?
And i can′t share backend or frontend because the installation actually is on local.
yours sincerly
Tania