Tomcat's server Locations configuration

At the time of development, we sometimes find that our deployed projects will be deployed to other directories in addition to the WebApps directory, where we need to double-click on a server locations modifier on the Tomcat server pop-up page in eclipse inside the server view. But this time is gray, if you want to change, we need to remove all the items and then right-click Clean, when the page opened again this item can be modified, my project is inexplicably deployed to the Wtpwebapps directory, modified after redeployment, debugging success.