Knowledge Check Questions

See if this approach is to your liking. Adobe Captivate - Custom eLearning Interactions - YouTube

You can easily set up slides that do this without using normal Quiz Question slides or Knowledge Check slides.  Just use normal buttons for the answers.  As soon as the user clicks the correct (or incorrect) answer, set the button action to do whatever you want. 

The submit button on quiz slides is basically there to delay things and allow the user the option of changing their mind and choosing a different answer before they actually submit the answer for assessment.  If you don't have the submit button then you can only usually have questions that boil down to choosing one answer.  Selecting that answer then invokes an immediate response.

But what if you wanted the user to select two or three of the options presented (i.e. the equivalent of a multiple response quiz question slide)?  Then how is the question supposed to know when to invoke the action?  When ever you have question types that are more complex than straight multiple choice or True/False, that's when a Submit button makes good sense.

Knowledge slide are based on the same maser slide as normal quiz slides. Almost all the functionality depends on that Submit button. When the learner decides to be ready to submit the answer(s) he should click that button and the two-step submit process starts. If you want something else, you can develop custom question slides, using interactive objects and advanced/shared actions.

Comparsion of quiz slides and KC slides in this blog post:

Knowledge Check Slides - tips - Captivate blog