Issue with the DropDown list

I am having three drop down list each drop down list referring to each entity like

In the web Page I am using the three drop down list like

In the preperation I filter the Bus accoding to the Location selected and Time accodring to the Bus Selected.

It works fine when we creating a new application but while editing it does not show the bus or time associated with the application filled out

So everytime I have to edit the application manually I have to select the Route bus and Time.How can I address this issue.Any help is greatly appreciated.

Is the dropdown variable of Bus and Time filled on preparation?
That seems to be the problem.