My film poster keeps getting changed after I put the right one with a professional account.

There are international posters for my film (the night eats the world), but I would like the french one (which is blue), the one I choose, to be the one that appears on the film page. I created an imdb professional account linked to the film to do that. And it worked. The problem is, imdb keeps changing it back to others versions of the poster (red ones), wich are international posters.
At this point I don't know what to do anymore.