Adjusting opacity is a great way to apply a less intrusive watermark or to manually fade in or out of a video.
To adjust the opacity in WeVideo, click on the clip in your timeline, and then select the line segment icon (to the right of the pencil icon). This will display a green line at the top of the video in your timeline. You can then drag and adjust the line to your desired opacity. When the line is at the top, the picture will be completely opaque, and when the line is at the very bottom, it will be completely invisible.
You can add additional keyframes by clicking anywhere on the line. This can be used to create a fade-in or fade-out effect.