Help me please!

I am going BONKERS over here!!  More often than not, when I try to post a comment on other people's blogs, it does not give me the "Name/URL" option for identificatin, even if I am logged in and even if I am already a follower on that person's blog.  When I try to sign in using my "Google Account," it asks for my log in and password (which I provide), and then it asks me to type in a word to check that I am not spam (which I do), but then it brings me back to the Google log-in page again!  Round and round in circles.  So frustrated.  Any advice or tips??  What am I doing wrong?