Over the weekend, I took some video on my wifes Samsung S23FE, which came out perfect.... on the phone at least.

When I copied the file to my PC and viewed it, it came out rotated 90 degrees. So I went into ClipChamp and rotated it correctly, but it stuffed up the aspect - not that it was a major. Was happy with the output, so exported it, and uploaded to Youtube. But on Youtube, the damn thing has rotated again. 

Any ideas how to resolve this ?