Hi,
The drop-down background is mostly inherent from the theme stylesheet, but you should be able to change their colors with this custom CSS:
a.chosen-single {
background: turquoise !important;
border: none !important;
}I also see that you have taxonomy terms as results, which cannot be affected by the filters. I think you don’t want to display those, so make sure that under the General Options -> Sources 2 there is nothing selected: https://i.imgur.com/RQwLYT7.png
Other than that, I cannot tell, I have to see your exact configuration, as well as the posts to see which criteria does not match and why. If you want me to check that, feel free to add temporary back-end access, and I will do that for you.
