new button
Right-click on the toolbar to which you'd like to add the button. It doesn't matter which one you click on, but the CUI will open directly to that particular one, saving you the tiny bit of trouble having to scroll to it in the CUI. Unfortunately, I already have made this button, so I'm not sure if it's in the list by default. In the Command List:, search for "Turn All Layers On". If it's there, simply drag it up to the section above where your toolbars are, and fit it between whichever commands you wish. If it's NOT there, click the New button. On the right will be the Properties of "Command1" and you will change the name to Layon, or whatever you like. The Macro is ^C^C_layon . Notice the space between layon and the period. That space acts as an ENTER key. Then you click on Turn All Layers On in the Command list on the left, and at the top right you can choose an icon. I suggest choosing the dark lightbulb, then coloring it yellow, nice & simple. Click Apply to see if it shows up on your toolbar, then OK if all seems well. My apologies if this isn't very clearly written, but I'd be happy to help more if necessary.