Reply To: I am trying to scale up the radius of skin modifier, but when I am hitting CTRL+A I unselect the vertex. How can I scale i…

If you changed the default CTRL + A key shortcut to something else, I don’t think you’ll be able to scale the radius of a skin modifier mesh. Another reason why I force myself to adhere to default key shortcuts.

I recommend reverting your shortcut keys to default to get back that functionality with the skin modifier.