Slider not responsive anymore

We are using a free version of the slider and just realised it is not responsive- slider is not adjusted for the mobile screen, I need to scroll horizontally to see all testimonias in mobile.
Is there also an option to set amount of letters are shown for the testimonial? Some longer text is not displayed and it just cuts off the text.

Thank you for advice!

The page I need help with: [log in to see the link]