Infopath choice field problem

Form designed in infopath, two drop down fields are set by external data source which is a share point list.

I have a primary field drop down list and a secondary whos values are determined by the primary.

But when a value is set in the primary and secondary, if the primary is subsequently changed the values in the secondary drop down list update but the previously selected value is still selected.

I assumed i could get around this with a bit of jquery in a script editor web part, clearing the selected secondary on change primary but the event doesn't seem to fire? alerts in there to check the change in functioning.

$(function(){
	$('#ctl00_ctl39_g_91c6fe7f_a544_4c53_ada4_3b366313e78e_FormControl0_V1_I1_D12').change(function () {
		var status = this.value;
     	         alert(status);
		$("#ctl00_ctl39_g_91c6fe7f_a544_4c53_ada4_3b366313e78e_FormControl0_V1_I1_D13").val(0);
	});
});