C# web browser save search engine settings

C# web browser save search engine settings

I'm working on a web browser where the default search engine is Google
until the user clicks on the Yahoo (or another search engine) button. The
problem is, after you start a new session, it opens with Google again. How
to you save that?
I'm aware how to save settings with Properties.Settings.Default.Save();
however it doesn't seem to work with a click event. (Where the code is to
change the search engine)
I'm using GeckoFX. Code for the Yahoo setting is:
goo.Enabled = true;
y.Enabled = false;
bin.Enabled = true;
ba.Enabled = true;
ya.Enabled = true;
sear.Text = "Yahoo!";
And is performed with:
if (y.Enabled == false)
{
W.Navigate("search.yahoo.com/search?p=" + q.Text);
W.Select();
}