How to change the default font in Microsoft Outlook from 'Calibri' to one you prefer more

To change the font in Outlook, head to the "Signatures and Stationery" menu, where you can pick from a number of fonts.

How to change the font size in Signal for your display and messages on a computer or mobile device

You can change your font size in Signal on the secure-messaging platform's desktop, Android, and iPhone apps.