Well the first problem you have is a bug where when you create a turret you 'spawn' one but also the turret created as part of the build tool is placed, so you create 2 turrets every time. That needs resolving first. Also when you create a turret its already upgraded because you are 'touching' it when you create it.
Now I´ve cleared the Event sheet and removed some bugs.
But still the same problem. All towers are shooting when set 1 to upgrade :/
(dropbox link is the same, like in reply befor)
If you want to try it, (hold mouse on purple sprite to open menu and double click on tower to open upgrade menu)
Edit: I think its cause I always use the same gun to shoot. It should be work if I creat another gun.
But I got another Problem, do u know how to fix the mouse part to touch part?
It doesnt worked with on touch object, instead of mouse. Also tried hold touch and touched object.
Re Edit: Still doesnt work. I created a new gun and placed on its old place. I have no idea how to fix it :X