missed this – but I am not sure how to adjust the fields downloaded and I don’t know if the “update” feature would respect the connection file changes. I think you need to contact Clarivate, if you haven’t already.
Tony M. (Technical Support Representative), recommends contactingTechnical Support
1-800-336-4474 option 4 then 1 (week days I think)
or
https://support.clarivate.com/Endnote/s/technicalsupport?language=en_US
They are there to help whenever you run into issues.