For accessibility purposes, you might need to work with bigger sized fonts.You might want to give all your worksheets a more personal touch by using your own signature font.The same old Calibri font may be boring, so you can use a different font to make your sheets and documents stand out.Many companies have their own fonts that they use as part of their branding strategy.Here are some other reasons you might want to change the default font in Excel. Changing the Default font in Excel by Creating an Excel Template.Changing the Default Font using Excel Options.