Unfortunately, HomeByMe is an online service, which means that you cannot access older versions of it. Once the web interface is uploaded, the new version will still on unless the developers decide to roll it back.
Also, for me, the interface is already in English, but in your case, it could be localized in a different country. Try using this address: https://home.by.me/en/ and make sure that the /en bit is there (it comes from English).
Lastly, the button to move between floors is now placed in the top left corner.