New learner vs. revisiting learner

Hi all,

I need to set up a set of courses (Storyline 360)  in such a way that a learner going through a course the first time is unable to skip pages or navigate ahead, but once they have completed the course, they can revisit any page, skip ahead, jump to specific pages, etc. Is there a way to do this? I know how to disable the Next button until timelines end and hide the Menu tab on certain pages or in the entire course, but I'm not sure it's possible to make these dependent on whether or not the learner is taking the course for the first time. 

Specifically:

• For new learner -- Menu tab hidden (or displayed but disabled). Next button disabled until end of timeline on each page. Learner must complete each page in order, cannot jump around or skip pages, and cannot proceed to the next page until the current one is completed.
• For returning learner (e.g. revisiting material before taking assessment at end of course, launching course again at some point in future for refresher) -- Menu tab that was hidden for new learners displays and is enabled for returning learner. Learner can skip ahead or jump to specific pages using Menu and Next button at any time during play.

I think it might be possible to use variables to manipulate when the Next button is normal or disabled, but I suspect the Menu tab cannot be hidden or disabled based on variables.

Thoughts? Thank you in advance for advice or guidance.