SharePoint Server 2013- How to edit an InfoPath Form that has been Published to a Document Library

We have users fill out InfoPath Forms which get published to a document library in SharePoint. How do I edit the InfoPath form after it is published to a library? I tried downloading a copy of the form but it opens on read only mode. I tried editing in the Browser but that doesn't work either.

I have the Form Template saved locally but I want to specifically make changes to a form that a user has submitted. How do I go about this?