V4 missing Modifier button

i have been using V2 and like it very much and was going to upgrade to V4 but i need the Modifier for the servers to make it work for me any help would be greatfull

Check below link:

if i install on my lapton can i move it to my store pc?

You can move your database file to a new computer very easily if you are using Compact SQL, or SQL Express 2012.
Which database are you using ?

Look here for help SambaPOS Database Configuration