Thinking about this a little more - when setting default values, you should probably put in a test to see if the drop-down was previously answers.
// Loop through all "defaulted" rows and set default answers
$(defaultedRows).each(function(i, value) {
// Column 1
if($('#question{QID} tr.subquestion-list:eq('+(value-1)+') select:eq(0)').val() == '') {
$('#question{QID} tr.subquestion-list:eq('+(value-1)+') select:eq(0)').val(3)
}
// Column 2
if($('#question{QID} tr.subquestion-list:eq('+(value-1)+') select:eq(1)').val() == '') {
$('#question{QID} tr.subquestion-list:eq('+(value-1)+') select:eq(1)').val(3)
}
// Column 3
if($('#question{QID} tr.subquestion-list:eq('+(value-1)+') select:eq(2)').val() == '') {
$('#question{QID} tr.subquestion-list:eq('+(value-1)+') select:eq(2)').val(3)
}
// Column 4
if($('#question{QID} tr.subquestion-list:eq('+(value-1)+') select:eq(3)').val() == '') {
$('#question{QID} tr.subquestion-list:eq('+(value-1)+') select:eq(3)').val(3)
}
// Column 5
if($('#question{QID} tr.subquestion-list:eq('+(value-1)+') select:eq(4)').val() == '') {
$('#question{QID} tr.subquestion-list:eq('+(value-1)+') select:eq(4)').val(3)
}
// Column 6
if($('#question{QID} tr.subquestion-list:eq('+(value-1)+') select:eq(5)').val() == '') {
$('#question{QID} tr.subquestion-list:eq('+(value-1)+') select:eq(5)').val(3)
}
});