Manage submission on back end

I would like to manage the progress on form submissions on the back end. Is that possible? i.e. I can add columns to the spreadsheet summary that will allow me to add completion date, etc.  Currently, when we download the excel spreadsheet it starts fresh every time and does not save changes.

Possible?

That is possible, you just need to add a hidden field, so the column will be shown in your submissions grid. In that way you will be able to assign any value to that hidden field through the edit mode, here is an example: https://www.jotform.com/help/194-How-to-assign-a-status-to-submissions 

Let us know if you need more help.