I'm having difficulty with the Captcha as well. I created my forum (
http://jtdh2005.freeforum.ca/index.php) a couple of days ago. The Captcha has 5 options available as plugins, but the only one that will work is the GD 3D Captcha, which is nearly impossible to read. For my own account, it took five tries to get a Captcha I could read to register.
I would prefer to use the Captcha without GD, but would even be happy to use the Q&A Captcha. Unfortunately, no matter which option I choose, after clicking "Submit" and returning to the User Registration page, it has defaulted back to the GD 3D Captcha.
Is there any solution for this? Thank you, in advance, for any assistance in this matter.