Looking for the ability to change text displayed on buttons

On my "Who We Recognize" page we offer an asset at the end of each section. I am looking to change the text on the button which currently is defaulted to say "Download Case Study". My problem is that they are not all case studies; some are eBooks, infographics etc. Can you please let me know if I can update each button on this page using Custom CSS. If so, what would I need to add to the My Custom CSS plug in?