The size of the canvas of a genially can be modified. This option is useful for creations that are started from scratch, or in other words, for ones that don't use a template.
Here are the steps to follow:
1. Open the left lateral menu Background.
2. In the lower left-hand part of this menu you'll be able to see the tab CANVAS SIZE. Click on the arrow to unfold the available options.
3. Edit the canvas size with the measurements you want in pixels.
4. Once you've entered in the desired measurements, click on the button .
In this video, you can see the described steps: