format data displayed on Excel data entry form

[Bob, too]

I am using Excels "built-in" data entry form to input elapsed time which is
formatted as [h]:mm:ss in the bound cell. Entries are captured correctly and
displayed correctly in the bound cell (e.g., 25:26:27).

However, after the leaving the record and returning to it, the data entry
form displays the times using AM/PM rather than 24 hour format, and for times
greater than 24 hours formats it as a full date in dd/mm/yyyy h:mm:ss AM/PM
format (e.g., 1/1/1900 1:26:27 AM).

Can I cause the data entry form to use my desired format? If so, how?