JL might be doing the Control + 1 or 2 or 3 as the shortcut to get the subdivision level he desires. And that’s why it looks he is turning on or off the modifier.
As for the lines, do you mean you want to not have the modifier results showed when you enter edit mode? If it’s that, you can just toggle the “Display Modifier in Edit Mode button”. In the modifier, it’s the one next to the screen display icon.
