Hi Vanessa,

If you want to set every time field's AM/PM to PM, you can use the following JavaScript:
 

$(document).ready(function() {
  $(".timepicker-type-dropdown").val("pm").change();
});

Alternatively, if you only want certain ones to default to PM, apply the CSS class timepicker-pm-default to those fields and then use the following JavaScript instead:

$(document).ready(function() {
  $(".timepicker-pm-default .timepicker-type-dropdown").val("pm").change();
});