Enable Modify My Request
As a JSM administrator, you can enable Modify My Request per project from the settings of any Jira Service Management project.
Once you enable it, the button Modify My Request will appear in every request from this project on the Customer Portal.
Portal request can be edited by:
Creator
Reporter
Portal request cannot be edited;
if there is a resolution set for the ticket
if edits are disabled in Jira for this request status