Why isn't my slider filling up the screens width?
Width limitation on the slider's container
If it doesn't work, you will need to create a new module position or modify the CSS code of your template, so that every container of the slider would have 100% width. If you are working with WordPress, try the PHP publishing method.
Overflow: hidden on the slider's container
It's also possible that the slider size was calculated correctly, but one of the slider's container has an
overflow: hiddenCSS code and a limited width, which prevents you from actually seeing the slider where it would be outside of this container. You should inspect the codes that are making your slider's parent elements, find this code and remove it.