Dependent Dropdowns with form submission.

Ok so let’s keep the dropdowns your way and click each dropdown in the properties panel and add a onChange event. Inside that event add

$w("#myDataset").setFieldValue("fieldkey in your data collection", $w("#dropdown id here").value);

So whenever someone changes the dropdowns it will set the value to your field using that code above and then when you save the dataset this values will also be saved.