Can I file my 2020 tax return using my 2019 AGI if it’s more than my 2020 AGI I’ve already filed my 2019 return so I was just wondering

No, you have to file your tax return using the income and other information for the current tax year, 2020. 

Isn’t this wrong. On the irs websites it states that we can use our 2019 income if it greater than our 2020 income so we don’t lose our EITC and other tax credits. So this is very confusing cuz I’m trying to figure out where I can put my 2019 income for 2020 on my taxes. They said line 27 on 1040 form but with turbo tax not sure where that is 

Yes, you are correct.  you can use 2019 income instead of 2020 income to calculate the Earned Income Tax Credit and other credits.  According to the IRS, if your earned income was higher in 2019 than in 2020, you can use the 2019 amount to figure your EITC for 2020. This temporary relief is provided through the Taxpayer Certainty and Disaster Tax Relief Act of 2020.  To figure the credit, see Publication 596, Earned Income Credit.

How do I use 2019 earned income in TurboTax 2020?

1. Type Earned Income Credit in the search box.
2. Click to Jump to earned income credit.
3. Answer the questions presented on the screen.
4. Click yes for "Do you want to use last year's earned income?"
5. Enter your 2019 earned income. 

You would never report your 2019 income on your 2020 tax return.  Your 2020 income is whatever your 2020 income happens to be.

Separately, there is a function in the program to calculate your EIC based on 2019 information, but that is not the same as reporting the income and paying tax on it as if you earned it in 2020.