It depends upon the scope you have selected. There are two scope settings – Application and User scope.
From MSDN article:
Application-scoped settings are read-only and are shared between all
users of that application. These settings are stored in the app.config
file in the section. At run time, the app.config
file will be in your bin folder and will be named with your
application’s name (MySettingsDemo.exe.config).User-scope settings are specific for each user. They can be read and
set safely by the application code at run time. These settings are
stored in a user.config file. To be technically accurate, there are
two user.configs per user per application—one for non-roaming and one
for roaming. Although the Visual Basic 2005 documentation states that
the user.config file will be named according to the user’s name
(joe.config), this is not the case. The user.config file is created in
the:
<c:\Documents and Settings>\<username>\[LocalSettings\]ApplicationData\<companyname>\<appdomainname>_<eid>_<hash>\<verison>.