I don't think https://Yahoo.com.com/ is a valid URL. Try changing it to https://www.yahoo.com and see if that works. You were in the right place, but I just think the URL might have been the problem.
Sorry it was my miss typing here. it is just as you stated.
Opening firefox now "MSN" is home page.
I clicked on the lock and moved it to the homepage house. MSN reared its ugly head.