I see the PowerPoint presentation full screen, and the audience sees the PowerPoint program

It sounds like you may need to adjust your order of operations.

Please try launching the PowerPoint in presentation mode (full-screen) first and then sharing that full-screen window via Zoom.

If you share the PPT application before launching the slideshow, the screen-share has no idea that you're looking to share the full-screen presentation, as they're treated as two distinct window IDs.

If you have more than 1 monitor, this will be easy - just make sure the full-screen presentation is on its own monitor and then share either the fullscreen application or that whole display.

If on a single monitor, you'll need to toggle windows in order to find Zoom and initiate sharing (Windows+Tab, etc), then toggle back to the presentation.

I have the same "problem". In one computer I can start 1st sharing the PowerPoint program and when I start presentation mode, zoom swiths and will show it automatically. At the other computer same "problem" related here (I need to share only after starting presentation mode). Any ideia what I need to adjust to have the same automation presented in the 1st computer?