If you're resident for tax purposes, you'll fie you tax return Form 1040, resident tax return. You don't need to submit form 8833. As for Form 1042-S (code 20), you can enter that follow these steps
Select Take me to my return
From the top, select tab Federal Taxes /Wages and Income
Scroll down to Less Common Income section
Choose Miscellaneous Income
Select the very first option at the top "Other income not already reported on a Form W-2 or Form 1099". Then follow the prompts.
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