Case Comments - related list not customizable
|Knowledge Article Number||000214311|
|Description||User would like to display the case comments based on created date ascending or descending and allow users to choose to display case comments based on created date ascending/descending.|
|Resolution||Case comments based on created date ascending or descending is not a Salesforce functionality.
Currently there is an idea listed for this feature. The more votes this idea receives the better of a chance that it will be reviewed by our Salesforce team.
A possible workaround would be to move forward with creating a Visual force page which can have an "customizable" date option. This would allow the user more flexibility. Since this deals with coding you would either need to request the help of a developer or take the steps with your companies designated developer.