The nectar slider has a few CSS classes you can add for different effects/behavior. A nifty one we created as a bonus is called "static". What it does is make it so the caption / buttons move at the same speed as the background in a parallax slider. By default it moves slightly faster, but this might always be desired if you for example are trying to make the text look like it's on an object rather than in front of it.The class to use is called "static".
Another one similar to that is called "caption-no-fade". It will also stop the parallax effect on the caption content, but in addition it will stop the opacity fade as you scroll down as well. This will in turn make the entire slide move together. The other possible css classes are "external-button-1" and "external-button-2".
Their names are pretty self explanatory, but adding either of them or both of them will
cause the button(s) for your slide to open in a new window if you want your link to be
In summary, here's a go-to list of all the Nectar Slider classses that come by