Change in app language

Ok. I have a Finnish acount in app store. My Iphone 5 is in swedish. Siri is in english. But why are som of my apps bought in App Store in german? I can speak Finnish and swedish and english but not so much german. In my settings the international language is swedish. Im connected to the finnish appstore (language in appstore isswedish). Siri is set to english (swedish and finnish not optional). Where else can i change languages? Som of my apps are in german (I buy them from the finnish appstore) For example i bought FileBrowser for over 5 €, its in german and I cant use it. Several other apps, same problem. Please help me. I went to an apple store to ask but they only checked which language I have my settings on. And then they arrogantly told me that i hace to change my app store location. I showed them that its Finland and the then told me that they just couldnt help me.

Please, does anybody know how to help me?