Please see the attached video on creating a small customisation that allows control of the fields when "Copy" is used.
CA Service Desk - Control Fields Being Copied
There is a SPEL file called 'tmplcopy_site.spl' which controls which fields to copy when using the copy functionality on a ticket in CA Service Desk Manager.
To customize this file to meet your needs, you must make a copy of the file which is located in $NX_ROOT\bopcfg\majic, and put it in $NX_ROOT\site\mods\majic, then customize the one in the site\mods\majic directory.
This customisation is not supported by CA Support, as it involves editing a spelcode file.
CA Support cannot assist you with customizing this file, but can only provide the information on where the file is located.
Alternatively, you may contact CA Global Delivery to request this customisation be done in such a way that it will be supported between upgrades.
Or you may engage CA Services or a CA Business Partner to perform the work on the current version, but without the upgrade support (unless purchased separately).
Having said that, this customisation should be able to be managed in-house if a regular Administrator with customisation experience is present.