Asset layers such as videos, effects, generators, and images, that are added to Surfaces have their own properties that can be adjusted.
How to change general Asset properties
Click on an Asset layer and the Properties Panel will slide in from the right side of the screen.
The opacity and blend mode can be changed.
The position, scale, and rotation of assets can be changed.
The asset can be modified so its perspective fits the Surface or this can be reset.
The asset's style can be modified.
How to change Effect/Generator properties
Built-in Effects and Generators have an additional section in the Properties panel.
If a preset exists for this effect or generator it will be displayed in the dropdown menu.
How to change Video properties
When a video is imported onto a surface, the surface or slide containing the video remains the same length (typically 10 seconds). Under the video properties, you can "set slide duration" to have the length of the slide match the length of the video.