By default, your ClockIt: Easy Schedule Creator duty roster is displayed with three headers:
In the first, the year and the month are shown, in the second the week number and in the third the day number.

In the settings (Menu > Options > Settings) at the Schedule Look > Display Options, you can modify the number of headers to show, as well as the information to display :

ClockIt: Easy Schedule Creator - Display Settings

With this option, some predefined variables are available, and identified with a %, but you can add custom text as well.

Following variables can be used:

Day
%j : Day of the month without leading zeros.1 to 31
%d : Day of the month, 2 digits with leading zeros. 01 to 31
%D : A textual representation of a day, three letters. Mon through Sun
%L : A full textual representation of the day of the week. Sunday through Saturday

Month
%n : Numeric representation, without leading zeros. 1 to 12
%m : Numeric representation, with leading zeros. 01 to 12
%M : A short textual representation, three letters. Jan through Dec
%F : A full textual representation of a month. January through December

Year
%y : A two digit representation of a year eg 08
%Y : A full numeric representation of a year, 4 digits. eg 2008

A special variable is /n which is used to display the date information on different lines.

For example

the value %D %j /n %M /n %Y will display following information:
Sun 1
Jan
2008

the value %j %M %y will display following information:
1 Jan 08

You can select a predefined format from the list, or you can add your own display format by combining the given variables with your custom text.