To change the default system font, you will need to find the entries for ‘Segoe UI’ (the default font in recent versions of Windows) and replace them with the font of your choice.

Learn how to customize the default font, color, size in Microsoft Outlook desktop client. You can easily increase the size if it is too small.

QUICK ANSWER To change the default font in Outlook on Windows, head to Settings > Mail > Compose and reply, then select your default font and size under Message format.

Better ClearType Tuner helps you fix blurry font issues & apply the same font-smoothing on multiple monitors if you are using Windows 11/10.