To access your Appearance preferences, choose File > Preferences > Appearance.
(On a Mac, choose Moneydance > Preferences > Appearance).
If you're using Moneydance 2020 or an older version, you'll find the settings relating to "Appearance" (font size and theme) within General preferences.
Choose from multiple colour schemes, or select "customize" to create your own.
You'll find more information about themes in this article.
Choose your preferred font from the drop-down list.
As above, the font that is used for numeric characters.
The font used when printing reports, graphs or cheques.
Select +1, +2 etc. to increase the font size.
Or select -1, -2 etc. to reduce the font size.
If your appearance changes are not applied to the entire program, restart Moneydance.