The edit icon appears when you hover your mouse over a comment. When you click it, it opens the standard form for adding a comment:
The following users can edit comments
- the person who wrote the comment;
- the manager of the person who wrote the comment
- the project's client-manager, if the person who wrote the comment is an external user.
Only the person who wrote a comment can edit its actual text. The other users listed above can only edit additional information, such as data tags that are attached.