Changing application setting in Unit test

I have created a unit test in a separate project. I am trying to change a filepath I have as a setting in the main project. I access the path as My.Settings.FooBarPath. I can't figure out how to change it in my unit test. How do I access the settings in my main project from the unit test project and how do I change the values?

I have read this post: Modifying application settings in unit tests

The second answer seemed to be the most useful but I couldn't quite seem to get it to work for my unit tests.