It sounds like your keyboard is set up for the United Kingdom instead of US layout.
Change keyboard to US (English) layout in Windows, then the '@' symbol will type by pressing the key that it's printed on (you still need to press 'Shift' first of course).
For Win7: Control Panel >> Region & Language >> Keyboards & Languages
If it's Win10 I don't know, never used it, but I imagine it's something similar.