Don't use Selected Label for this purpose. Use Selected Value (Or selected string value, if you must).
Avoid bidirectionally binding dropdowns directly to control tags. Dropdowns have an unavoidable hiccup when starting if the data is bound. Instead, add a custom property to each dropdown to which you bidirectionally bind your control tags, and then uni-directionally bind the dropdown to the custom property.
Then add a boolean custom property (I call this "Dirty") that is true when selected value != custom prop. Use this to style the dropdown to signal that it doesn't match the "live" value. (I typically use yellow background for this.)
Finally, add an "apply" button to the window that is enabled when any dropdown has Dirty true. The script would unconditionally copy from selected value to custom property.
If desired, also include a "reset" button that refreshes the selected value binding on all of the dropdowns.