You are setting the intended default value in the expression field. As far as I understand webstorm live templates, expressions are for dynamically inserted values like `user()` for the users name or `date()` for the current date. I don't know if this is something which can be generically converted from Sublime Text to Webstorm, as those are rather IDE specific.
But what we can use are statically defined default values, which are the values after the : in Sublime Text templates.
`${1:10}` here **10** should be the default value for the first variable the cursor should focus.