Hello ! I'm Aymeric, an independant advisor, and I'm here to help !
What exactly do you mean by testing ActiveX controls ? The ActiveX controls are only supported in the Internet Explorer mode. Just go to the page that requires ActiveX content, and a message should pop out at the bottom of your screen, prompting you to install the required certificate.
Please note that ActiveX has been deprecated years ago, and is not safe or secure by today's standards. Try to keep ActiveX usage to a minimum, to avoid any malicious software installation on your PC.
Feel free to ask if you have any other question !