Open the video in a video editor or player with rotation tools
Find the rotate or orientation setting
Rotate the video 90 degrees clockwise or counterclockwise
Preview the video to confirm it is upright
Save or export the rotated video
If using a phone, use the built-in edit option in Photos or Gallery
If using a computer, use software like iMovie, VLC, Windows Photos, or a video editor
If needed, re-export the video in the correct format and resolution