Start Menu is a key element in Windows 10 to correct what’s wrong in Windows 8 and 8.1. That’s why it’s been updated so often that it changes in every released built. I recall that in one build the resize feature was disabled and can only be re-enabled through a registry change. I also recall that there was an maximize icon in Start menu that could easily turn it to the full-screen mode but you don’t find it in build 10122.
While the feature that lets us to change the size of Start menu has come back, how do we set the Start menu in full-screen mode if we want to?
Go to Settings → Personalization → Start, and slide full-screen switch to On in Start behaviors section.
The change takes effect immediately. Now when I click Start button in my Windows 10, I get this instead:
To change the size of the Start menu, you will need to disable full-screen mode first and move the cursor to the top edge of the start menu to change the height and the right side to change the width of the start menu. Unfortunately, you can’t change the height and width the same time for some reason.