Trying to connect to the same site(s) from Chrome, I get a "valid CA" message regarding the YAHOO certificate (see image) - no AVAST CA in the middle (at least not mention in a message...) .

Hi, I have AVAST anti-virus. Trying to connect to my YAHOO site (and many other sites) from Firefox , I get an "unrecognized issuer" message regarding the AVAST CA: i.e. the avast certificate is not recognized (see image) Trying to connect to the same site(s) from Chrome, I get a "valid CA" message regarding the YAHOO certificate (see image) - no AVAST CA in the middle (at least not mention in a message...) . My question: Why ? Best, Avi