Velocity of flexslider

Hi all,
I’m new to grav and have the following question:

I use Ceevee template with flexslider. As far as I have found out the velocity of the slider should be set in the Flexslider Default Settings line 1045 of jquery.flexslider.js (themes - Ceevee - js).
But changing the setting there has no effect.
What can I do to set the slideshow speed?

Thank you!