Keeping layers visible?

Hi Tony and welcome to E-Learning Heroes. 😊

Thanks for reaching out and sharing what you would like to create. Without seeing your file, my first thought is to be sure that:

1. There is not a trigger to hide the 4th layer
2. Slide properties are set to resume saved state.

With your permission, I'd like to take a look at your project file to investigate what's happening. You can share it publicly here, or send it to me privately by uploading it here. I'll delete it when I'm done troubleshooting.