How do I change the source monitor's aspect ratio to be vertical 9:16?

[ColdPizza]

I am using Premiere Pro on Windows 10. I am editing a vertical video and I changed the program monitor to 9:16 aspect ratio however when I open any clips in the source monitor panel, the monitor is set horizontal 16:9. I applied a 'transform' master clip effect to the files to get them in the right orientation but that doesn't make the source monitor flip.

How do I do this? Thank you.

[Ann Bens]

Post screenshot sequence settings

and clip in MediaInfo in treeview.

The SM will open the original file> if its 16:9 so will the source monitor regardless of source effect.

If uou open a vertical clip from the timeline in the SM then it will show as vertical.