Html_entity_decode or encode

Hello

I have import with API an old wordpress website. All is fine now. But when I edit some post I can see html code ans not the real characters :
From
culture "projets et accompagnement"
To
"culture "projets et accompagnement"

How I can force change it into all post ?
rake posts:remap ? An existing regex ? An feature or plugin ?

Thank you if you have any idea.