player trigger

If you want to do that for every slide, you don't need any triggers. Just set the Player to use Restricted Navigation.

Here’s how Restricted navigation works:

• Storyline puts the Next button in the Disabled state when the user first visits the slide.
• Storyline changes Next to the Normal state when the slide’s timeline ends. Simply adjust the timeline to adjust when Next will be enabled.
• Next remains in the Normal state whenever the user revisits a completed slide.
• This works even if you don’t show the built-in Menu.
• If you do show the built-in Menu, users will be able to click the Menu to jump to any previously view slide. But they won’t be able to click the Menu to advance to a new slide.

This post has a more info about controlling the Next button, including for slides with interactions: https://community.articulate.com/discussions/articulate-storyline/tip-controlling-the-next-button-101