EdinburghtoLondon

Hello, I have a bit of an odd question. My telephone is in French, but for a variety of reasons I need to use the app in English. I downloaded the app before logging in through a browser; in the browser I was able to change the language to English without issue, but the app remains in French, and I cannot find a way within the app to change its language. Surely there must be a way to change the app language without changing the entire phone's language; how can I do so? Many thanks!