Realm error message

I can open the current realm but need replace the realm with a different one I've made so I can download my world to a different device. It either comes up with failed or error. When searching this issue it lead to a problem open from 2017. I have contacted support as I should surely be able to change realms, but they just sent me to you. I have tried many times, on both devices to reset or replace the world. It hasn't been working for the last few weeks.