Saving option that is selected in dropdown field

The problem I am having is on page reload the selected option reverts to placeholder.

How can I save the select option in a dropdown field so that it is the default option?

I would tie it to an app variable. Maybe also tie the placeholder text to that variable as well if it doesn´t work straight away.

Yep I have done that but when the app is closed and reopened it is back to the default option in the dropdown field.

You need to use one of the database solutions like firebase.

I think this is covered in the tutorials. They really are quite good and will get you heading down the right path.