How to change all fonts in VB.NET all at once?

No, you have to either skin your form: Skinning form VB.NET[^] which will mean changes to a lot of your existing app, or use the Control.Controls Property (System.Windows.Forms) | Microsoft Docs[^] recursively to set your font height in your form constructor. Bear in mind that changing the font size will not alter the size of controls, so expect clipped text or tiny text in big buttons, etc.

Generally speaking, automated font sizing doesn't work well in Win Forms from a user perspective.


And ... generally speaking, font size is a user decision: make text smaller than default, and it's hard for them to read, make it bigger and you start to look "Fisher Price". The chances are your app will start to look ugly, or patronising if you aren't really careful.