How to Prevent a Ticket from being Automatically Reopened in Response to a Customer Reply
By default, when the end-user or customer responds to a ticket, the status of the ticket is automatically changed to Open.
If you don’t want to reopen a ticket on customer reply, you can customize this behavior by unchecking the checkbox shown in the screenshot.
For changing the behavior, go to Admin > Fields and Forms > Ticket Fields > Status > Edit.
Note: You can customize the automatic reopen option for all custom and default statuses of the tickets except the ticket status of Open, New, and Waiting for the customer. To learn more about how to create and customize the ticket status, read this article.
Access Permissions
For editing the Status field values, an agent should have the Manage fields and forms permission assigned to his or her role. Refer to this article to know more about the roles and permission.