How do I change the default font of Sticky Notes?

There are workarounds.

If you cut-and-paste text from another program, let's say Word, to a Sticky Note, that note will take on the original fonts the text was in.

To change size, luckily there are keyboard shortcuts...

Ctrl + Shift + > makes the font bigger

Ctrl + Shift + < makes the font smaller

There is a complete list of keyboard shortcuts available here.

I know this is an old question, but I have an answer that might be better than deleting the font, but will still render the Segoe Print font useless. In the registry, you can change the font that Windows thinks is Segoe Print and Segoe Print Bold

1. Navigate to: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Fonts
2. First, export that key so you have a backup.
3. Find Segoe Print (TrueType)
4. Change the value to the file name of any other font that you wish to use that is already installed (navigate that registry key to find others).
5. Do the same for the "Segoe Print Bold (TrueType)" and match it to the Bold version of this font.
6. Then, log out and back on.

Here's a .reg file you can just double-click that will change the Segoe fonts to the Consolas within the registry. Created and tested working on Windows 8.1 Preview

stickynote_font_fix.reg

Linked code:

REGEDIT4

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Fonts]
"Segoe Print (TrueType)"="consola.ttf"
"Segoe Print Bold (TrueType)"="consolab.ttf"

Log out and the font used by the Sticky Notes app should be legible.