Soft reset

Does pressing the volume and on/off button on the iphone make the phone revert back to (some) factory settings. I don't want my children to have access to the App store. It is usually not even visible in the app library because of all the restrictions I have in place, but it seems after a soft reset it came back? I question, because I spent so much time locking the phone down, that I don't know if that is what did it.