Change the path to a Data Feed in a PowerPivot workbook

Creating the datafeed files, published them to the document library and if you wanna change the server name / change the site name in the datafeeds then here is the solution:

http://www.powerpivotblog.nl/import-data-into-the-model-using-a-macro-in-excel-2013/

This workbook cannot be opened because it is not stored in a trusted location - SharePoint 2010 / 2013

If you are facing the following error:
This workbook cannot be opened because it is not stored in a trusted location. to create a trusted location, contact your system administrator

then here is the resolution: 
http://sharepointknowledgebase.blogspot.com/2011/12/this-workbook-cannot-be-opened-because.html