Where is the updated version of 'appname.config' file is saved, after we make some change to it?

See more:

C#

config

Whenever we update some user setting by calling the following code (Here the property name is given as 'SomeProperty')

Settings.Default.SomeProperty = TextBox1.Text;

And save it by calling the save method like the following code

Settings.Default.Save();

The value of 'SomeProperty' is changed, and I can see it as I load that value in a label in next run of the application. But when I try to manually find the updated value of 'SomeProperty' from the 'app.config'
or 'app.exe.config' file I find that the value assigned to 'SomeProperty' while creating it is there(Not updated).

Can anyone please tell me where is the updated version of the .config file is saved?

What I have tried:

I have no idea about why this is happening, and what is the remedy..