When updating a New or Open ticket you can select a canned text response from the list

It will show the general Canned text Responses and any filtered responses that relate to event type of the ticket

The chosen response will be populated in the comment field and will be saved in the ticket history once you have pressed one of the following buttons - Close Ticket, Save Ticket or Apply New Comment.

By selecting the Make this comment public the end user reporting the problem will be able to see the comment.