Slider doesn't resize correctly
Theme issues: slider in table tags or the container has fixed with defined
When your slider's upscaling/downscaling only partially looks like it's working, then the problem will be with some css code in the template/theme in that part, where the container of the slider is. You should check out this documentation to figure out what css code is causing your problem. Usually it's that the slider is inside a table, display:table, display:table-cell, or simply table tags, or there is a fix width, min-width or max-width is given, or one of the containers have float on it. If it's float, that usually can be solved by giving width css code to that element, but if it's something else, you should remove it, or put the slider elsewhere, try to use the php code instead from the publishing options, where you have full control, where the slider will be, so you could put it into a place, where there aren't any containers besides the html and body tags.
The slider just partially responsive
If you resize the window and the slider only partially follows the change, that can happen that you are using the Adaptive responsive mode, which is not responsive, so if you would like your slider to be 100% responsive, you should rather use the Auto responsive mode.
The imaged doesn't scale