App resets itself to the default language

I’m using the app pinterest, and the default language for my phone is set to korean, because it’s my first language. I still have english and japanese on my phone because I also know those languages. I’ve been trying to set the language for pinterest to english, and I do this on the settings app, but every time I exit out of the pinterest app after changes the language, the language resets itself to korean, and this is so annoying. Does anyone know a way to make pinterest stay the language I actually set it to be without changing my default language from korean to english?