I think I saw this before but can't remember how to do it. I want to know how can I go quickly to the script associated with a button on a layout.

thank you

Layout Mode | Right-click the button | Specify Button | Perform Script | Specify

But is there a way to quickly edit this script ?

You could give yourself a shortcut key to open script dialog. You need to open the script dialog to quickly go to (and edit) a script, unless it's a simple Specify Button script-step (in which case you can edit as transpower indicated). Once the script dialog is open, you can type the first letter of your script name and it'll jump down to it.

If you give yourself a script to open script dialog, be sure it is protected so others can't accidently run it.