All day clock settings are accessed from the RecallCue app on your phone.
You can change the default labels and times for time of day. For example you you can change the "early morning" time of day to "it is very early" and change the time that shows from 4:00AM to 3:00AM. A good example of when this is useful is when the days start to get shorter in the winter and longer in summer.
To set custom time of day settings:
From the home screen click on the menu icon in the upper left hand of the screen.
Select "Day Clocks" from the menu.
Click on the day Clock you want to edit.
Find the "Custom Time of Day" option and turn it on.
Set the new label and/or time of day for that label
Click the Save button
Like all clock settings these are unique per clock so make sure you adjust on all the clocks in your account if relevant.