How do I change the overridden feature to default
Features takes configuration from the database, and stores it as code. When a feature is "Overridden", this means there's a difference between what is stored in the database, and what is stored in the files.

This can happen because you've made changes directly to, for example, the Views that are exported. However, it can happen for less obvious reasons.

Sometimes, when you enable a new module, this module may add additional data with a default value to the export of a module. This suddently means that when Features compares the db and files, there's more data in the db, and you have an overridden feature.

Because there are a large number of reasons you can end up with overriddes, there's no surefire way of handling them. You need to install the diff module to inspect that the difference actually is. Then you can determine if you want to "Revert" the feature (copy the Feature file data into the database), or "Re-create" it (create new Feature files, which you can then overwrite the original feature with).