On the category page, the filters are scrolling with the page

In this case if you want the filters don't scroll with the page, you need to customize because in fact that it's our design. 

I regret that this is out of support scope. However, If you want, you will need to pay a fee to make it because we don't make it free. 

If you agree, please let us know and we will sent a mail to you about this fee.