It's always best to set up the display on a page using the text mode instead of the visual mode. If you use visual mode the shortcode is wrapped in
tags which can lead to unpredictable formatting as the themes css for the code tags will take precedence over the plugin's css.
[katb_testimonial group="all" number="all" by="random" id="" rotate="no"]
Pagination will work if you display all testimonials or all testimonials in a given group so the key tags are group="something" and number="all". The group name can be anything but if you want all testimonials put in group="all".
Meeker, can I ask what you are trying to do with the above code?