Conditional Trigger for Submit button

Assuming you are in a published mode and not just previewing a slide. 

When you click submit, it makes sense that the progress bar moves because you have a trigger to add 1 when clicked. If you click and it adds 1 and moves to the next slide, then you shouldn't see the submit button to click again. So that should solve it. 

However, if you do continue to see the next button, then you need a condition such as T/F to determine if the submit button was already clicked.

Two other ideas

One thing you could consider is getting rid of the +1 on submit and just adding +1 when the slide starts. So they submit, jump to next slide and +1. If you do that, then you need a similar condition to determine if the slide was visited.

For example SlideVisited = F. When they click submit on the slide, you can change that variable to True. Then when they come back the SlideVisited is True. The trigger for progress would be Add 1 to Progress when slide starts on condition that SlideVisited = F. 

Another idea is to use the slide progress variable. You can scroll down to see what's available here: https://articulate.com/support/article/Storyline-360-Built-In-Variables