Hi,
If I understand you correctly, I think you’re saying that the green and red playback bounds are changing automatically? If so, it’s because you have turned on a setting, “Keep Playback Range in Section Bounds”.
This setting keeps the playback range bounded by the bounds of the keyframes and sections (like camera cuts and audio clips). This is normally off by default for Sequencer, but some some users like to have the option so we’ve exposed it. If you use UMG’s Sequencer, it will be on by default because UMG users prefer to have that behavior.
Hope that helps.
-max