Watch-only mode is an optional feature that allows you to log in to a Blockstream Green wallet with limited permissions.
You can update your wallet's watch-only mode login details via your mobile wallet's settings.
1.
On your wallet's home screen, tap the Settings icon in the top right corner then select Watch-only login.
2.
Enter your new login details and tap Save. You can then log in to your watch-only wallet using the credentials.