Slider settings - Slider size - Responsive mode - Fullwidth
Your slider will have 100% width, and auto height based on the given slider size.
Responsive - Full width
Minimum height for your slider not to let it go too small and Maximum height not to let it go too big. These values are based on the slider's size, so for example if you want to have 500px minimum height, that is: 500 / slider height * slider width
Force full width
Originally your slider can be only as wide as the container it is in, but with this option you can force it to go outside its containers, and make it as wide as your screen is. This option has limitations, so it won't work in every case, and you will have to put your slider into your template or theme.
Maximum width not to let your slides to go too wide. (This will only restrain the width of the layers, but the background image will still strech out to 100% width.) You can also choose to give a different maximum width for tablet and mobile views. If you choose to give them, then the Remove vertical marginoption will change the slider's size for tablet and mobile views, to make it have it's original ratio.
Would you like to see some example on how the Full width responsive mode is working on real sliders? Check out these demo sliders: