TT wants me to fill in Form 1116 Explanation statement showing the other deduction items for line 3B column A but I can't see my form 1116 to see what line 3b col A is

Line 3b of Form 1116 is used for deductions not related to your foreign source income. 

Line 3a is used for most itemized deductions and 3b is used for Schedule 1 deductions like student loan interest, self-employed health insurance, IRA deduction, alimony paid, educator expenses, etc.

If you are using TurboTax Desktop (from a disc or download), you can click on the white Forms icon in the upper right corner. Highlight Form 1116 in the left column and you can see the form in the reading pane. 

In TurboTax Online if you have paid, you can generate a PDF of your tax return from the Print Center:

1. Click on Tax Tools at the bottom of the left side menu.
2. Select Print Center below that. 
3. Click on Print, save or preview this year's return. 
4. You will be prompted to pay, if you haven't yet.
5. Select the option to include Government and TurboTax worksheets. 
6. A PDF will be generated, which you can save or print for review.