Thread:Project:Support desk/Multimediaviewer extension - how to use description rather than image filename/reply

for example on this page : https://www.mediawiki.org/wiki/Help:Images/fr#mediaviewer/File:Example.jpg

It display text "Tournesols" not the actual picture filename (Example.jpg) But on my mediawiki it would display Example.jpg instead of Tournesols despite I put a text description like: