You have several locations where you can change your video’s name!
In the workspace:
You can change your video’s name while editing your project. Hover your mouse over the title in the upper left corner of the workspace, and click on it to open the edit field.
From the Share page:
You’ll have the option to change the name of your video on the Share page too! Click on the name of the video and that will open the edit field so you can change the name.