How to set NDMP environment variables?

OnTAP 9.4 4-node cluster

I have Commvault as my backup software and I need to set NDMP HIST variable to no on the NetApp. I have a really hard time finding out how to set it. Could somone point me to the steps to set this up? I see some posts on setting the environment variable during ndmpcopy session but it apparently does not apply in this case.

thank you.