You can rename accounts via your Blockstream Green desktop application. The changes you make will be reflected across all other devices that have access to the respective accounts.
Note: Make sure you understand the difference between wallets and accounts.
1.
On your wallet's home screen, select the account you want to rename.
Note: You can rename every account except for your main account (the default account that comes with your wallet).
2.
Click on the account name.
3.
Your account name is now updated.
