Formatting a worksheet can take almost as much time as creating it in the first place. Worse still, you design it to look one way and minutes later your boss comes along and wants it to look different. If you use styles, you can make your changes almost instantly; if not, you're in for a long day.

Styles save time by allowing you to apply a series of formats in one step and to change formats very easily. When you click the Percent or Comma toolbar button, for example, you're actually applying a style even if you don't realize it.

To see Excel's built-in styles, choose Format | Style. You can then choose a style from the drop-down list to apply to the currently selected cell or cells. When you select a style name, the remainder of the dialog shows the features that are applied with that style. Some, like Comma [0], apply only a number format, while Normal applies a range of formats including Borders, Shading, and so forth.

To create your own style, choose Format | Style and type a new name in the style name list. Click Modify and select the options to apply with this style, such as font size and type, alignment, borders, and shading. Now return to the Style dialog and click Add to add the style to the list. Similarly, alter a style by clicking its name and choosing Modify.When you're done and you've returned to the Style dialog, click Add to confirm the changes.

The toolbar buttons for Currency, Percent, and Comma are linked to those styles in the Style list. To change how these buttons work, simply modify the style; every cell that is formatted using that button from now on (and all cells you previously formatted with it) will display the new style settings.

To make creating a style simpler still, you can use any formatted cell as the starting point. Just click in a cell formatted as you want, then choose Format | Style and type a name into the Style name box. The attributes of the style appear in Style dialog and all you need do is to click OK to create it.

Two toolbar buttons can make accessing and using styles much easier. To add these buttons, right-click a toolbar, choose Customize, then choose the Commands tab and locate the Format category. Drag and drop the Style... button onto a toolbar to access the Style dialog, or the Style: button to access the list of styles. When you add buttons to toolbars, they remain accessible through successive sessions of Excel, but the styles you've created won't. Styles are limited to the current workbook, and they aren't available to other workbooks unless you do something to make them so.

There are two options that you can use to make styles more accessible. One method is to merge styles from one workbook into another and make them available that way. To do this, make sure that both files are open, then switch to the file into which you want to import the styles. Choose Format and Style, and click Merge. When the Merge styles from: dialog opens, choose the workbook containing the styles to merge, and then click OK. If there are styles of the same name in both workbooks, you will be asked if you want to merge those with the same name; answer Yes or No as required. This is a blanket option—you can't select which styles to merge; it has to be all or none.

While this process will let you merge styles from one workbook to another, it is cumbersome if what you really want is to change the default styles or to add some more of your own styles to the list. In this case, save the styles in the default workbook template. This is a special file called book.xlt that contains all the settings for all new workbooks. You may already have a file called book.xlt, so use the Windows Search or Find tool to search for it. If it is there, open it, add your styles and modifications to it, and then save it.

If you don't have a book.xlt file, start a new blank workbook and configure your styles in it. Choose File | Save As, name your file book.xlt, and, from the Save as type drop-down list, choose Template (*.xlt). Navigate to your XLstart folder, which, for Office 2003, is generally C:\Program Files\Microsoft Office\Office11\XLStart, and choose Save.

Now all your styles will be available automatically to all new workbooks, but the workbooks you created before the change won't be affected. To alter these, use the Merge option to merge styles from any new and open workbooks if you want the styles to be available to them.

Helen Bradley is a contributing editor of PC Magazine.