Why is TTx auto-claiming 8K FED out of 10K & 10.6K Prov out of 11K from my Unused Tuition for 2018 Return?

The amount of tuition credits used is determined by your taxable income and your non-refundable credits.  Your student loan interest is being carried forward because your tuition credits already covered enough credits so that you do not have taxes payable.  

Tuition credits don't expire and the amount used is an automatic calculation.  Student loan interest can be carried forward for 5 years.

If you are comfortable using Forms Mode in TurboTax, you can search for Schedule 11 to see the calculation for your federal tuition credits.  For the provincial tuition credit calculation, you can do a keyword search for 'tuition' and your provincial S11 form should show up in the list for you to view.  For student loan interest, you can search for "LOAN" to see the calculation.

Let me rephrase my question: Based on the numbers I shared in the original question, Ttx pre-calculates and uses an amount to be claimed even if it is not necessary since without using the "Unused Tuition and Educ Amt. from previous years and my tax return is already on a refund status? I have filed income tax last year for 2017 and this was not the way TTx did the calculation.
--- Please note Fed amount claimed from Unused carry forward 10,074.23 with ZERO 2018 total tuition fees (AT this point I have $910 in refund status) BUT Ttx took Amount claimed NECESSARILY in 2018 = $ 7,983.78 with Maximum amount available to transfer
equal to 0.00 of course.
--- And for the Provincial amount: TTx took the Unused tuition and education amounts from previous years = 11,167.87 and your software claimed in 2018 more than necessary a huge $10,633.78?

Kindly elaborate why this calculation seems weird.

The calculations on Schedule 11 are not based on your refund status.  The amount of tuition that can be carried forward to next year is determined by a formula in the Income Tax Act, which considers your tax payable for the current year if only certain specified non-refundable tax credits were claimed.  TurboTax's calculation is based on that required formula.

Thank you Sarah. One last question hopefully you get to answer before the 30th April deadline-- "How about if I elect to share portion of the current calculated claim (without using the designated amount to carry forward) to one of my parents since it will help reduce their owing (around $125) ?

Unfortunately, unused tuition from prior years is not eligible for transfer.  

Thanks a lot, this was really very helpful.