Grid default value
You can add default values to the grid using one of the following ways:
Using grid configuration page
Select Add-ons in your Jira Settings
Locate Table Grid admin menu
Navigate to the Grids tab
Select desired grid to edit
Add Grid default value in the corresponding section
Using Grid Custom Field configuration
Select Issues in your Jira settings
Click Custom Fields in the Fields section
Find the grid custom field and Configure.
Select Edit Default Value in the Default Configuration Scheme section
Enter default values and click Set Default