Changing testimonial slider word length

Hello, I’m trying to figure out how I can change the excerpt length in the client testimonial slider I have on the bottom right of my site. I’m using the free theme Biography.

The testimonials cut off too early so I need to change the word limit somewhere. I’ve tried changing/adding CSS and PHP code in theme files but no success so far.

Thanks for any help!

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