Apply Group Configuration to Instances
Set Group Configuration
To set group configuration the first time or promote an instance's configuration to be the group's configuration, navigate to the Instances tab of the group and pick an instance you would like to promote its configuration to the group configuration then select Set as Group Configuration from its menu. After confirming the action, the group will take configuration

Update Group Configuration
On the Configuration tab of a group, click Edit, make your changes and click Save to save changes without applying the changes to instances.

Apply group configuration to instances
On the Configuration tab of a group, click Apply Group Configuration and select instances you would like to apply the group's configuration to, then click Apply Configuration.

The console will let you know if the configuration can be applied to instances and it will be sent to instances when the instances check in.