How to set iCloud account as default user on Apple TV?

My iCloud account is the Additional User. I removed the Default User and now I want to make my account the Default User but it is not letting me. I go through the steps to add a Default user and it tells me "Apple TV wasn't able to add you as a user. Please wait a moment and try again" I tried multiple times both by entering my password manually and through my phone but nothing is working.

If I delete my account will I lose everything?

[Re-Titled by Moderator]