Laying Out and Formatting a Chart : Formatting a series : Formatting numbers, dates, and times : How to format a date and time
 
How to format a date and time
 
1 In the chart builder, navigate to Values Series and choose Labels.
2 In Values, select date-and-time data to modify, and choose Format Editor.
3 In Data Type, choose Date/Time. Figure 17‑107 shows Date/Time options.
Figure 17‑107 Format options for date-and-time data
4 To use a predefined format type, select Standard, then specify the following format options:
*Select a format value in Type.
*In Details, select Date or Date Time.
5 To use a custom format pattern, select Advanced, then type the custom format string in Pattern.
6 When you finish defining the format, choose OK.