hi @loicbahuetu-oss Welcome to community froum 
Collabora Online has a simplified menu bar compared to the full desktop version. Many menus and options are either relocated, reduced, or absent entirely. The full Tools (Outils) menu from LibreOffice/Collabora Office doesn’t exist in the Online version.
In the View (Affichage) menu rather than Tools — in some versions of Collabora Online, the formatting marks option has been moved there.
Thanks
Darshan