VidLab is a multi-track editor, meaning you can add text, images, music, sound fx and voice recordings as individual tracks. This way, you can adjust what parts of the videos you want these tracks to appear, their animation, and volume if applicable.

To add a track, tap on the "Add Tracks" option in the tools:

From here, you can choose to add text, images, music, sound fx or a voice recording to your project as a new track: