Changing Default in a command in Excel 2003

[MPerlman]

I put the default toolbar button to insert a cell on a worksheet. However, I want to insert it horizontally and not vertically. If I use the menu, it gives me the option to change it to horizontally for that instant. But if I use the toolbar button, then it does it vertically automatically. Is there a way I can chenge that default so that it will automatically insert it horizontally, unless I change it back?