First thing I noticed is that Managed fields do not appear on the list for obvious reasons. As I was testing on an instance containing managed solutions and so I had to create a new field.
I needed a way to change the type of field from integer to text. Since dynamics will not allow you to do this without recreating the field , I had to look for other options as I would like to keep the data.
Came across Attribute Manager in XRMtoolbox with the best disclaimer I have ever seen