Excel uses a 10pt Arial font by default, but that doesn’t mean that you have to live with it. Sure you can change the font manually at any time by simple selecting a new font style and size from the Formatting toolbar, but if you want Excel to always use a different font style by default, it’s an easy switch.
To make the change to the new font style and size that you prefer, simply click Tools > Options and then click the General tab. Use the drop-down arrow next to Standard font to pick your preferred font, and then choose a new font size from the Size option. Click OK to implement your new settings. From then on, Excel will use the font style specified for all new worksheets you create.