To change the default for the current spreadsheet:

• Select Format | Style and make sure Normal appears in the drop-down menu.
• Click Modify and make the appropriate formatting changes on the Font tab.
• When you click OK and go back to the spreadsheet, any text you enter will appear in the new format you've selected.

To change the default font for all Excel spreadsheets

• Choose Tools | Options | General.
• Restart Excel for the change to take effect.