How to set variable to Properties.Settings.Default instead of setting name?

Question

For example I do save to App.config like this:

int SaveInteger = %ANY INTEGER%
Properties.Settings.Default.X_Position = SaveInteger;
Properties.Settings.Default.Save();

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I make a string variable that contains the name of the setting, depending on the work of the program:

string Some_Setting = %ANY SETTING NAME%;

So the main question is how i can set variable Some_Setting to Properties.Settings.Default.%SettingName% instead of setting name?