Can I edit the captcha on the forms? Is there a different type of Captcha than the one automatically available on the form?

Can I edit the captcha on the forms? Is there a different type of Captcha than the one automatically available on the form?

My users are having trouble reading the captcha and are not submitting the form.

Is there an alternative to captcha on the forms? An simple addition 3+6=?, or a JS created-checkbox?

Please advise.