Comments on observations
There are two places where you can enable comments on an observation.
The first is during observation creation.
In an observation, select the comment bubble in the observation. A message will confirm the action by saying Comments enabled. You can select the bubble again to disable comments; again, a message will confirm the action, this time saying Comments disabled. You will also notice a line through the comment bubble when comments are disabled and no line through the bubble when comments are enabled.