It is very simple to change the video settings in Android, therefore very simple to change them accidentally.
If you open each video clip in Handbrake it will show you what the format was, as recorded, in terms of pixel size, frame rate, and encoding. Then on a separate tab you simply set what output you do want for video and audio. I would recommend HD (1920 x 1024,), 30fps Constant frame rate (CFR), H264, mp4 (leave audio as it was recorded) and it will convert and save a copy in that new format.
Dave
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