To edit an expression after you’ve created it and closed the window, you must know how to find the expression in the Expression Editor. The next steps show how to find and edit the expression. Specifically, you’ll change the expression to alter how quickly the scaleY value changes.
If you don’t see the scaleY attribute, scroll through the Attributes list as necessary. You can also use the Select Filter menu option to customize how you search for your expressions within the Expression Editor.
The expression you created previously appears in the expression text field:
Ball.scaleY = time + 1;
Ball.scaleY = time/5 + 1;
By dividing time by 5, you’ll make the Y scaling increase one-fifth as fast as with the previous version of the expression.
Note that you can use the keyboard commands Ctrl-c (Windows and Linux) or Control-c (Mac OS X), Ctrl-x or Control-x, and Ctrl-v or Control-v to copy, cut, and paste text in the Expression Editor and elsewhere in Maya.
Clicking Edit does the same action as clicking Create. Create exists only for new expressions. Edit replaces Create when you display an existing expression.