Hi @codeoner,
I hope you are well today and thank you for your question.
You have to change the slider posts publication dates to change the order of slides in the slider.
If you don’t want to change slider post dates then you have to develop custom code as described in the following topic.
https://colorlibsupport.com/t/sparking-theme-randomize-posts-in-slider/#post-116140
Best Regards,
Movin