Vertical exports often lose information that seemed obvious in landscape: a hand, a product or the second person. The solution therefore starts before the export dialogue. Create a dedicated version whose framing and graphics have been checked for the narrow format.
Make a copy with a clear purpose
Duplicate the approved source sequence and name the vertical version clearly. Set the required aspect ratio and pixel dimensions. Edit this version without silently changing the landscape one. Record whether both editions should retain the same content and duration.
Inspect each clip for its essential subject. In an interview that may be the face; in a tutorial it may be a hand or display. A fixed central crop cannot account for those differences. Position the image according to the action and check the beginning, middle and end of moving shots.
Crop or redesign
If a broad subject cannot fit meaningfully within the narrow composition, do not force an unintelligible crop. Another shot, a redesigned graphic or deliberate visible borders may preserve the information better. The purpose of the image matters more than filling every part of the frame at all costs.
Automatic reframing can save work, but requires inspection. Check whether the crop jumps between faces or follows an irrelevant foreground object. Manual keyframes should be calm and support the action. A continually chasing virtual camera can become tiring to watch.
Check text and output separately
Rebuild titles and captions for the new width. Long lines may need different breaks or positions. Keep names complete and avoid covering important action. Merely shrinking the whole landscape layout frequently produces undersized lettering.
Export a short representative passage and play it on a genuinely small display. Inspect the visible area within the intended player where known. Controls may overlay parts of the image. Do not rely entirely on a generic guide in the editing interface.
Then check the complete vertical file, including sound, beginning, ending and every title. Match its language and version to the filename. A successful landscape review does not automatically apply to this edition because reframing and text layout can introduce their own faults.