The clone operations copy all custom fields from the parent issue to the cloned issue. However, it is possible to exclude the custom fields from being copied, if you want. This page provides details on how to exclude some custom fields or system fields from being copied.

Steps

Sign in to your Jira instance as Jira administrator.
In the top navigation bar, select JIRA Administration > Manage apps.
The Manage apps page is displayed.
In the left sidebar of the Manage apps page, select Clone Plus for Jira.
The Clone Plus for Jira Configuration page is displayed.
Select Clone plus properties > Edit tab to edit a copy of the currently active configuration.
Or
You can also create a clone-plus.properties file in the directory configured as your JIRA home directory or copy and modify the example clone-plus.properties file.
Add the following sample code where you provide a comma-separated list of custom field names or Ids that you want to exclude from being copied:
# Custom fields not to copy to cloned issue. Default is no fields excluded. # This is a comma separated list of exact field names or field id (like customfield_10100). # Double quote names containing a comma. fieldExcludes = custom2, custom three, Sprint
Click Make Active.
Once the Jira administrator has done these changes and the users clone any issue using the Clone+ and Clone++ clone operation, fieldExcludes will be applied.

If you also have customized clone operations, each of the customized operations control the fieldExcludes that apply to the custom operation in a similar manner.
If you want to use the same list of custom fields to exclude in the customized operation, add fieldExcludes as shown in the sample code. For example:
# Customization for clone 1 operation # Exclude fields from the global list and add another field to exclude for the custom operation 1.fieldExcludes = ${fieldExcludes}, "some other custom field"