To highlight the cells referenced by an Excel formula, click into the cell with the formula, and press Ctrl-[ (Ctrl and the open square bracket key).
Excel highlights all the cells referenced by the formula, and selects the first referenced cell. Press ENTER to move the cell pointer to the next referenced cell.
How do you get this to work across an entire Workbook rather than just on a single sheet (my old version of Excel did this automatically, but my new version does not)
Not sure what you are asking. Are you using the Spreadsheet Auditing to see the cells referred to by a formula? Select the cell with the formula, use Formulas|Trace Precedents, then double-click on the dotted line that appears.