Why 9:16?
YouTube Shorts, Instagram Reels and TikTok are all built around a phone held upright. A landscape (16:9) video uploaded as it is shows small with empty space above and below, so reframing it for a 1080×1920 vertical screen gets far more attention.
Blurred backdrop, fill or whole picture?
When the subject sits in the middle, fill gives the most immersive result. When the edges matter, use whole picture or the blurred backdrop, which fills the empty space with a soft copy of the same video instead of black bars.
Show the middle larger with 4:3 or 1:1
With the blurred backdrop or whole picture, a 4:3 or square ratio cuts out the middle of the video and shows it larger in the tall frame. Move the cut to the part you want to show, or type your own ratio.
Keep captions clear of the app’s buttons
Shorts and Reels lay titles and buttons over the bottom and right edge. Raise the captions a little and turn on an outline or box so they stay readable on bright scenes. A title at the top tells viewers what the video is about before they swipe away.
Polishing captions further
“Edit in the editor now” opens the same layout in the AGONECO Video Editor, where you can retime and restyle captions frame by frame, add music and effects, and export MP4.