Hi,
When you Start on the W2, TurboTax will ask you Whose W2 you want to work on where you can choose
If you have already started with your Spouse's W2, Finish it and once you are done with it, You will encounter a screen asking Do you or Spouse have another W-2 to enter - see the screenshot
Click Yes there and it will again ask you if its for you or your spouse.
Hope this helps,
Thanks.