You actually don't have to do that anymore.
Once you click on an app, and it gives you that error..
Go to the same spot above they are talking about, and you will see something that says "APPNAME was trying to install...words words words..." and you can click "Allow" and it will launch that app again. This way you can keep your settings secure, but still let that 1 app install and you do not have to change your settings.