Thank you for posting your inquiry here in Microsoft Community, ChunWaiChuah.
May we ask for a clear picture of your type cover?
When you say alias key, do you want the @ symbol to show on the screen?
If yes, try to use the US (QWERTY) keyboard. Go to settings > select Time & language. > choose the Region & Language section. > Click on your PC’s default language under the Languages section. > Select Options from the expanded menu. > On the new Language options page, tap the ‘Add a keyboard’ option. > Scroll to the top of the pop-up menu and select US (QWERTY). > Remove the other keyboard language that were added on your device.
Hope this helps, otherwise let us know so we can further assist.