Should I use my 2019 tax return for my 2021 taxes for a bigger credit? not sure why its asking me this.

Because of the pandemic, a number of taxpayers saw sharp declines in their income in 2020 and 2021. However, some tax credits depended on your current year income (2021) to calculate the size of the credit. So in some cases, Congress allowed taxpayers to use income from a previous year to calculate the credit, if it increased the size of the credit.

So the answer is that it is OK to use 2019 income for whatever question this is, but you should compare the results of your tax due or refund both before and after you make this election, because there is no guarantee that using 2019 income would actually increase your credit.

Give it a try and see how it works out.