How to add new video or audio segments in an HLS playlist?

Got it! Thanks. But why does FFMpeg HLS video transcode and generate partial playlists?
Like in my case, whenever I try to transfer the basic mp4 video into the HLS video via FFMpeg using the following command:
ffmpeg -i SampleVideo_1280x720_10mb.mp4 -codec:v libx264 -codec:a aac -strict experimental -start_number 1 out.m3u8
No doubt it manages perfectly and generates the .ts segment files, It does manage to generate all of the .ts segment files, but the end outcome is any previous segments are omitted from the m3u8 playlist file, which only lists the final four segment files!
Any suggestions on that?