To set the default password you need to modify the variable default_admin_password to the desired value in the config file
/etc/capsule8/capsule8-console.yaml. Please see below the required field to be modified.
console: default_admin_password: "Password"
default_admin_password : Please input your choice of password in this field
This will only change the default user’s password once, to the supplied password. After restarting the Console to pick up this change, the configuration can be removed.