Hello Ethan,

For the property to stick you would have to update the database. It isn't very common to update this so you would have to update the property via: https://docs.q2developer.com/api_references/q2_sdk/db/db_objects/user_account_attribute_data.html

Just curious why are you trying to update the label? Updating the account nickname is far more common via: https://docs.q2developer.com/api_references/hq_api/q2_api/ChangeEndUserAccountNickname.html

Thank you,
Trey Teter