The settings dialog allows you to configure how DbgHelpBrowser searches for symbols.
The symbol search paths section allows to specify locations on your computer that hold debug information for the DLLs you may wish to use with DbgHelpBrowser.
The Add... button allows you to choose a directory and add it to the list of directories that will be searched for PDB information.
The Remove button will remove any selected directory, the Remove All button, will remove all directories.
The Set Default button restores the default search path of c:\windows\symbols\dll.
In the image above we can see the user has created their own directory c:\MicrosoftSymbols to store all the symbols from the Microsoft symbol server.
You can reset the settings to their default state at any time by clicking Reset.