Hi!

I followed these steps.

How to create a new style
Select a style within the customizer.
Hit Copy and enter a new name to duplicate the style.
Now you can start customizing your own style.
Once you are satisfied with your adjustments, hit Save and the customizer saves your style LESS files into the /styles/STYLE-NAME/style.less folder and compiles the CSS files into /styles/STYLE-NAME/css folder.
Please NEVER customize the pre definied style. Copy a Style at the customizer section and then you can edit your duplicated style.

And then

I copy the style "blue" and rename it "salento-sisters"
in Templates: Edit Style > Layouts I selected I chose "salento-sisters" style.

Problem: in front-end the displayed theme is "grey" style.
Can you help me, please?

Website: www.salentosisters.it

Thanks

Hello,
please delete all existing layouts.
Maybe a layout is assigned to a menu item and a style

Thank you!
I selected the same style for each layout, and now it works...
it's ok, am I right?

You are right..

Problem solved.