Using Variables to Disable Next & Returning to a Slide

LisaRoberts-691​: A “when timeline starts” trigger runs every time the user reaches the slide—even if the Slide Properties are set to “Resume saved state.”

Thus, all of triggers that set the variables to False and the trigger that changes Next to Hidden run when the user revisits the slide.

As EmileHusson​ said, you don't need any of the triggers to change the variables to False. Simply have False as the default value.

As for the trigger that hides the Next button, add conditions so that it will only run if any of the variables = False. To do that, connect the conditions with "or" (not "and"). 

For reference: TIP: Controlling the NEXT Button 101 | E-Learning Heroes 

BTW, according to the User Guide, this is how Storyline "automatically decides" what to do when revisiting:

• If the slide has only simple objects—text, images, audio, video, etc—but no interactivity, Storyline 360 resets the slide to the beginning of its timeline.
• If the slide contains interactive elements, such as buttons or other objects that have a visited/selected state, Storyline 360 resumes the slide where it left off previously.

Note that the revisiting settings do not directly impact variables. A variable maintains its value until a trigger changes it.

Here's what I recommend for the “When revisiting” setting in Slide Properties:

• Keep "Automatically decide" for graded-question slides. Storyline will know whether to reset the slide (when the user needs to answer the question) or resume it (when reviewing).
• For other slides, change the setting to ensure it does what you want.