Copy fields between records (not move) RM

I want to copy the “contents” of one field to another field for a set number of references it does not appear to be Intuitive. Can somebody please advise.

(That is for Record 1 field (12)=field(13), Record 2 field (12)=field(13), Record 3 field (12)=field(13),

NOT copy one field to all records)

First search for your subset of references (e.g. search for a range of RefIDs), then while you are on the Retrieved results tab, copy your fields. It should only copy fields for your retrieved references. 

Thank you Sarah, don’t think it solves my problem:

Example

field[31] DOI for record 3799 equals 10.1111/j.1474-919X.1939.tb03959.x

I want to set field [33] for record 3799 equal to Weblink equal to http://dx.doi.org/10.1111/j.1474-919X.1939.tb03959.x

Then replicate the process for every record in the catalogue.

It is easy enough to copy http://dx.doi.org/ to every field [33] but to append the relevant field to every record is the problem.

I’ve thought of exporting the catalogue to Word and writing a macro, but feel convinced there must be some means within RefMan

regards