How to make Settings.settings data permanent

Question

I have a Windows Forms application and I use the Settings.settings class to store the user configuration (email settings, subject, etc.). I did not understand that after the user closes the application, the settings are gone!

This application will be released, so I must provide the solution as soon as possible.

Answer 1

You need to save them after installing them. You tried:

Properties.Settings.Default.Save();

Answer 2

Do you use them like that?

... changes ...
Properties.Settings.Default.Save();