How to rotate a video

I have some videos from when I went to Rome but when I view them on my laptop, they only show it in landscape. I have tried to edit these videos using OpenShot only but I am struggling to make progress with this but do not know what else to do or what else to use.

OpenShot had no effect with these videos whilst saying that it could create and edit movies and videos.

If anyone has any ways of getting me to get video(s) from Landscape to Portrait quickly, easily and with no hassle, it would be greatly appreciated.