Keep narration easy to hear
When combining speech and music, lower the music volume so it supports the voice. Listen through the whole sequence, especially where the narration begins and ends.
Video editing
Add narration, background music or a sound effect, then line it up with the action. Control your audio separately from the picture.
Sign in to edit. Export is available after your first balance top-up. Crypto payments are available with a 10% discount.

Add your video to the project and place it on a timeline track.
Import an audio file or open Voiceover to create narration from text. Generated speech uses credits.
Move the audio to the right starting point, trim its edges and adjust the clip volume.
When combining speech and music, lower the music volume so it supports the voice. Listen through the whole sequence, especially where the narration begins and ends.
Mute the video clip through its context menu if you want only your new soundtrack to play. Keep it enabled when the original ambience is part of the scene.
Yes. You can keep, mute or adjust the volume of the original clip while adding another audio track.
You can import your own audio file. Make sure you have permission to use the recording in the video you plan to publish.