When there are multiple element or designs in your project, click the "Select All" button to select all. This is very useful when applying property changes to the whole project. You can also visually (in the view window on the screen) rotate or scale the whole project quickly when all elements or designs are selected. You can tell that all elements or designs are selecting because a black box with eight handles will be surrounding all designs.
You can also select all through the "Project View" by selecting the project in the tree view, right click, and select all.
A Shortcut key for "Select All" is to hold down the 'Ctrl' key and press 'A'.