- Select the symbol on the button.
- Click either the Marquee or Lasso button.
- Click and drag to select the desired portion of a symbol.
- Right click and select copy region.
- Right click on the area you want to add the portion of the symbol to and select paste item.
Note: You can also click and drag out a marquee box with the Placement Cursor to set the position and size of the selected portion of the symbol within the button.