How to update Document Library file properties under folders using CSOM

Hi,

We have a document library with list of csv files under each folder.we have a custom site column named Status which is a choice field added to this document library.

I want to update the choice field value using CSOM.

When I am updating ,its updating the folder properties not the File properties under this Folder.

I am using a CAML Query and filter the files under the folder.

May I know the procedure to update File properties under folders using CSOM?

Thanks in anticipation