CSS ?ver=4.6.1 not updating

The version number ?ver=4.6.1 is coming from the theme’s call to the wp_enqueue_style() function. When the $ver parameter is set to false, the WordPress version is used for the ver query variable.

Making changes to your theme’s style.css file will not cause browsers to reload the new version of the file. To do that, you’d need to change the $ver parameter used in wp_enqueue_style() for your theme’s stylesheet. Alternatively, you can use a plugin such as Busted! to do this.

Also, child themes are the best way to customize your theme because editing the parent theme directly will result in your customizations to be lost when the theme is updated.