OK, it sounds like one of these things is happening:
-- you're not using the correct upload settings when uploading the video file;
-- you're not selecting the HD version of the video to play on YouTube; or,
-- the video file isn't properly encoded prior to upload
For the first one, what options does YouTube give you when uploading the video, if any? Also, it apparently automatically converts all videos to a 16:9 aspect ratio if they aren't already in that format (4:3 vidoes get "pillars" on the left & right sides).
For the 2nd one, understand that (like Facebook) YouTube by default shows a
lower quality video, unless you choose to watch a higher quaility version. Even videos that are uploaded at 720p or 1080p resolution, by default, will show up as either 320p or 480p. You can still watch the higher-resolution video, but you have to manually select that version (if it's available). Click on the gear icon & select the quality that you want.
For the last one, try:
https
/support.google.com/youtube/answer/1722171?hl=en
Appears to have recommended video/audio & format encoding settings to use for the video file
before uploading it to YouTube.
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