subtitles

Dear Amit,
I created a page called “Nouveautés” to write a subtitle under the title.
I wrote a few words on the section titles and subtitles of the page as it is on the page shop (called favoris in my website).
The link of this page which is ok: https://odecouvertes.com/boutique/
My problem is that the subtitle written in the same way on the Nouveautés page does not appear.
https://odecouvertes.com/boutique/nouveautes/
I configued the Nouveautés page as child of “shop”.
If I put that the page has no parent, the subtitle is displayed but I lose the layout of the products as displayed on the shop page (with sort by popularity, list or grid, side column, etc … ) and the shortcode [product_category category = “nouveautes”] gives me a nasty display of products.
How to display subtitles on “Nouveautés” page and keep the layout of the theme and the shop page?
Thank you very much for your help.

The page I need help with: [log in to see the link]