Dissolve and Transition Terminology. Setting slide duration

I want to create movie with each slide on for 8 sec, and a 1 sec. dissolve. I can't figure out how to do that.

The Document tab has Delay: Transitions time and Build time. I set those to 1 sec. and 1 sec., but not getting the desired effect.

The Animate tab is set to Dissolve > Duration 1 sec. and Start Transition > Delay 0.5 sec. If I set these to Duration 8s and Delay to 0.5s; the transition lasts 8s as I would expect.

But how do I set the time the slide is up (without transition) to 8s? I want the slide show to auto play. I will export this to a movie to use as a Zoom meeting background.

Summary: Slide show with each slide up 8s and a 1s dissolve between slides. For export to a movie.

Thank you. I'm sure the setting is hiding in plain site.

PS. I see that I responded to a similar question 6 years ago

PPS. I would do this in iMovie except it doesn't allow 4:3 photos which mine are. And it limits resolution to 1K and we are now at 8K.