Without seeing what you have in the course, I'll make some assumptions.
The slide probably has media like audio or animations that when the slide launches start to play.
There are a few ways to keep this from happening.
- Create a first cover slide that does nothing and they need to click a button to advance and that goes to the next slide to start the course...or...
- Create a pause timeline trigger when slide starts and then a start button to resume timeline
- Create a "start layer" and have a trigger that shows the start layer when timeline of the slide starts. Then add a button on the start layer to hide layer.
The main point is to create some sort of gate that stops the slide
