Unless you disable the Sequencer option, Blender will always output
contents from the video sequencer instead of 3D data from your 3D
Viewport. If you want to go back to the 3D Scene to change animation
aspects, make sure you disable the Sequence option to render it again.
In case you have to edit an existing render, use a different Blender
project to edit and cut the animation.
8.5.3 Converting images sequences to video
By adding an image sequence to the Video Sequence Editor, you can
convert that to a video file like an MP4. Add the image files as a Strip
and change the output settings to use FFmpeg. Pick the settings you
need for an MP4 file and start rendering it again.
That is the moment where you can convert an image sequence to a
video file, and also add sounds or music. From the Add menu in the
Sequencer, you can include Sound strips to the project.
Rendering a video from an image sequence will be much faster than
generating all the content from 3D objects. Since you already processed
the 3D content, it will be a matter of converting all the effects and
images to video.
8.6 Adding titles and text
Most animation projects need some titles in the video to display
information before or after the content. That could help you to add
credits to the video or a simple title for a project.