1. Login to Sniffie.
2. Navigate to your profile page.
3. Open the language preference accordion. It's the last one.
4. Select your desired language from the supported language list. As of writing this article (February 2019), English, Swedish and Finnish are natively supported. More languages, such as French, German and Spanish are coming soon!
5. Click "Save"
6. Your UI language is now whatever you prefer it to be.