Received my 2017 1098t with an adjustment made for prior year. Does it mean I have to amend my 2016? Do I have to attached a copy of 2017 and 2016 1098t with my 1040x?

It depends on the details of your adjustment.

If your adjustment was to account for a refund of educational expenses (i.e. you really had less educational expenses than you reported in 2016), then you will not need to amend your prior year return, but you will need to refigure the credit for that year.  Basically, you will wind up adding any adjustments to this year's return.  TurboTax will walk you through the steps necessary to calculate this adjustment.

In this year’s TurboTax, follow the steps below -

• Log in and select Take Me to My Return
• Use the search function to search for “education recapture”
• Click the “jump to” link
• Follow the steps outlined - one of them will ask you about if you have any adjustments 
• TurboTax will then prompt you with recalculating the deduction/credit for 2016
• There will be a detailed instruction sheet provided in the link to guide you in calculating the amount of recapture.
• After you have the amount (if any, because its possible it may not impact) of recapture, return to TurboTax and the next screen will ask you to enter the amount
• Any recapture amount will then appear on this years return with a tagline “ECR"

If your adjustment was to report additional educational expenses that you did not have on your first return, then you may want to amend your return to increase your credit.  But, $4,000 is the maximum expenses used to calculate the American Oppurnticy Credit and $10,000 for the Lifetime Learning Credit.  So, if your expenses are already over these amounts even without the adjustment, then it wouldn't benefit you to amend your return.