How do I change my widget's rotation speed or other options

If you're using a widget and want to change its settings, then edit the widget via WP Admin > Appearance > Widgets.

Once you create a widget, WP Admin > Testimonials > Settings, has no effect on it.

WP Admin > Testimonials > Settings is more for the use of shortcodes throughout your website.

 

My options don't work, no matter what I do

Read this.