Use the IIS Manager to edit web.config files

You can edit web.config through IIS instead of manually using notepad. If you haven’t had to do that yet, be glad but now you’ll know where it is.

Go into the Internet information Services Manager and expand the server and then sites. Go into the site (example: Default) and then into the subsite (example: Microsoft-Server-ActiveSync). Which the subsite is selected, go to Application Settings and it will list all the variables in web.config so that you can edit them here instead of via code.

I would suggest running iisreset from CMD afterward just to make sure it pulls the new settings.