I'm using Android 6 (Marshmallow). I shot a landscape video but must have accidentally started it in portrait mode, so now it displays full-screen only when holding the phone vertically. I should not need to upload the video to some other device and edit it, possibly dropping the resolution, and reload it to the phone. There should be a simple flag somewhere in the video file that tells the phone when to display the video full-screen. I want to simply flip this bit (without reformatting the images) so that the phone knows that this should be displayed full-screen when the phone is held horizontally. The Gallery editor has this feature for still photos, but when I edit a video I get some sort of advanced editor that does a ton of stuff I don't want. All I want is a "change the orientation" button, just like the one that the Gallery editor has for still photos. Am I missing something here, or is there some other software package that will simply flip the "orientation" flag on a video file for me?