Q: Where can I see the plugin settings?
R: Woocommerce settings->Products->Display
Q: Can I show products by country instead of hiding them?
R: Yes! Check an option – “Reverse the query”
Q: How can I hide products by currency?
R: First you need to install the plugin WOOCS – https://wordpress.org/plugins/woocommerce-currency-switcher/
Q: Products are not hidden. It looks like the location of users is not determined correctly.
R: GeoLocation provided by native woocommerce native API, so it should works perfectly . Check this with a VPN or use special services https://www.locabrowser.com/ To show GeoIP use shortcode [woohp_test_geoip]. If only one country is always displayed:
1 Check option 
2 Contact to support of your hosting