Icons and their effects are confusing
- The up arrow should sort the comments by their up votes: After that the comment with the most up votes is at the top.
- The down arrow should sort the comments by their down votes: After that the comment with the most down votes is at the top.
- The clock icon should move the most recent comments up.
And please color the selected icon. You should be able to tell by the color according to which criteria the comments are currently sorted.