Global configuration

One possibility how to configure which link types will trigger Copy Comment is to make an Jira wide configuration.

As Jira admin, open administration, go to the Manage apps section and find Copy Comment in the left panel. Just check the links you prefer to be synchronized and click Save. The change will take effect immediately. 

Project configuration

Second way to configure the Copy Comment plugin is to set only project specific links which shall be synchronized. Comments then will be copied only in specified pairs of projects with specific links between issues.

As a project administrator, open project settings and find Copy Comment in the left panel (few lines below Users and roles). 

Simply choose a link and destination project you want to pair with. Then click on Add. The change will take effect immediately.

Overview of linked issues

You probably would like to control which issues are linked together and Copy Comment does copies. 

issueLinkType = "relates to" AND project in ("Your project")

To prevent Copy Comment, simply remove the links (already made copies will not be deleted!).

Logs & Troubleshooting

To see more, inspect Atlassian Jira log.