To edit a document, from within the Document, click on the three dot menu icon to the top right hand side of the page and select Edit file details.

From here you can navigate to the relevant details that you wish to update, using the left hand side progress bar. 

Update the document details as required. 

To save the changes, navigate to the final step in the details progress bar, Set permissions, and select Complete.

The document has now been updated.

To note - you will be unable to upload a new document via this method. To upload a new document, you must use "Upload new version" on the document details page. This is to ensure a full version history is tracked.