I have the Movie Edit Pro Plus steam edition editor, and when exporting a video there's no "social media" options to resize a video to a 9:16 aspect ratio for smartphone viewing. Could someone please walk me through how to do so, please? Thank you!
1. Create new movie settings for the format you want (File>Settings>Movie). If MEP doesn't have the social media resolution you want as shown by Patient-X above, you can make your own: in particular, you put in the resolution and the ratio eg Width 1080, Height 1920, ratio 9:16. You can actually put in whatever res you like: I quite often put in 1000/1000 so the video looks nice on Whatsapp. If you use an odd-ball resolution and can't work out the exact ratio, just use the numbers themselves eg if your res is 640x576, in the ratio put in 640:576. MEP will work out the ratio for you.
You'll probably get a message about the video monitor changing shape: allow it.
2. Bring your video into MEP. You'll probably get a message that MEP wants to change the (newly set) monitor and movie settings to match the video file: Do Not Adjust.
3. Commence editing. You can use the Section or the Camera/Zoon Shot tools to mark out the part of your video that will fit into your portrait (in this case) movie screen.
Re Section, in the dropdown menu, choose "Like Movie" to get the correct shape. I think the "Movie Size" button is misnamed; it should say "video object size", although I'm still scratching my head over that.
4 For export, simply ensure the resolution and ratio are exactly the same as your movie settings; they should be. If not, put them in. Also, make sure you select "Streamable" in the Export Advanced settings. Whatsapp will then treat it correctly as a streamable movie, and not just as a file to be downloaded first.
And, use File, Export movie, not the up arrow button at the top right of the screen.
Select Video as MPEG-4. The dialogue should already have your Project settings if you did as indicated by @PATIENT-X, then do as @AAProds indicated to complete the process.
See this tutorial on setting up the program and exporting for 9:16 AR video.
I would advise using the appropriate Social Media sites own uploaders, this will avoid issues when they change their uploader requirements and the program does not get updated to use the new requirements.
This also gives you the opportunity to check the video before uploading.