One way is to go to a site that you visit regularly. And now, hold CTRL and turn the scroll wheel down to make the size smaller. The reason going to a known site is that you will probably know the size of the font/images, and its easier to tell if they are smaller/larger than normal. Also, most of the time, you can tell by just how clear (sharp) any text on a site is.
Ctrl + Z = Undo
ctrl + Z Ctrl +Z is undo for everything
Undo
control+z = undo
Ctrl - Y or the Redo button will do this, so they can be used.
Undo is Ctrl-Z. Redo is either Ctrl-Y or in some programs Ctrl-Alt-Z.
ctrl shift - reverses the effect of ctrl shift =
Although Ctrl + Z will undo most all commands before you save a file, if you accidentally undo too much you can always use Ctrl+Y to redo the undos in reverse order.
Ctrl + z.
The Undo is done by pressing Ctrl - Z.
You can click the Undo button or use the Ctrl - Z key combination.
There are many different ways to Undo in Photoshop. Ctrl + Z is keyboard shortcut for Undo last operation, Ctrl + Alt + Z is Undo keyboard shortcut. You can Undo and from Edit > Undo or from HISTORY panel (Window > History).