Style of quantity field

As written in Codecanyon comments, we use quantity field format with minus and plus on the left resp. right side of the quantity field. If using variation swatches the quantity field falls back to Woo standard (up and down arrows). Here you can see the difference in the first row of product loop: https://dev.weingut-bischof.at/wein-shop/. How can we prevent the fall back?

As this is an development site it would be great to have a guidance so I can transfer the changes to the live site if development is finished.

Many thanks,
Stefan