Is there a way for the instructor to override the unit completion markings so that a student will be directed to an earlier unit?
My students with on tablets find it inconvenient to scroll to the curriculum at the bottom (portrait orientation)
You can try using the new course status page for this.
Go to wplms->course manager-> course status template, and choose full screen, refer: http://prntscr.com/dz5eu2
In tablets and mobiles the curriculum menu will open in the side only.