Is it possible to change Stake username? or possible to transfer account to a new one, with the old stats? I think I had asked the customer support long time ago and they said it wasn't possible. Just wanted to check here if anything changed.
No.
The only way creating a new account, but will broke their term & condition. But you could make some deal with them, to closed your current account and created a new one... So you will not broke the multi account term & condition.
But, stats will never cannot transferable. You can tried contact support for these kind of deal or request.