There are two ways for you to add a logo to your video.
First, click the Overlay button, and you will find many Logo overlays. Select a suitable sample and click to add it to the canvas. Then back to the media part, drag the image you like to the logo frame.
Second, click to add a PiP to a storyboard.
Third, click the Replace button and select an image to replace the original logo.
You can change the shape of the logo as well.