In December 2018 release of Acrobat DC/Acrobat Reader DC, a new preference is added to make checkbox visible for comments. Update your Acrobat/Reader to the latest version by going to Help > Check for Updates.
In Acrobat DC/Acrobat Reader DC, you no longer see the option to flag a comment with a checkmark in the comment note.
By default, the checkbox is hidden. You have to enable the checkbox in preferences so that it is visible consistently for all comments. To enable the preference, do the following:
The checkbox is now available for all comments. To add a checkmark, select the checkbox next to the comment.
- Select a comment in the Comments list.
- From the options menu , select Add Checkmark. You can also right-click the comment and select Add Checkmark. A check mark icon appears on the comment.
For more information, see Managing comments