To open any existing edits, click on the main menu (the three horizontal lines on the top-left) and click 'Open'. Then click on 'My project' to see a list of your edits.

It helps to give each project a unique name to make them easy to find. You can rename your video by clicking on the title (it will say 'my video' by default) next to the main menu.

You can see both the main menu and the project title area in the image below.