This example will have you modifying your screen set. You should really make a backup copy of your screen set (or your entire C:\Mach4Hobby\ folder before you do any of this, just in case you make a mistake! Your screen set may be found in C:\Mach4Hobby\Screens\YOUR SCREEN SET NAME.set
To modify your Go To Work Zero button you your screen set, please follow these instructions:
1) Open Mach4 and your profile.
2) Click on Menu -> Operator -> Edit Screen
3) Click on the Go To Work Zero button, then click on the lighting bolt then click on the text "GoToWorkZero" and finally click on the "..."
4) Look at the lua code associated with the button. In this case the GoToWorkZero() code is a function inside of the screen set's Screen Load Script. Just go ahead and close this ZeroBrane Studio editor window.
5) Click on your screen set's name (TMC3in1_v16 in this example), then click on the lightning bolt, then click on the text to the right of Screen Load Script, and finally click on the "...".
6) Scroll down through your screen load script until you reach the desired function, GoToWorkZero(). In my case, I am not using the A axis, so I will remove the A0 from the commanded GCode. Make the changes you desire, and then save and close the ZeroBrane Studio editor. I usually compile before and after I make changes, to make sure that there are no mistakes: Menu -> Project -> Compile. Fix any mistakes if it reports any.
7) To close the screen set editor, click on Menu -> Operator -> Edit Screen to close. Click on Yes to save the current screen.
8) Enable and try your modified Go To Work Zero button code.