I already submitted my federal tax refund but need to edit it and it wont let me apply my overpayment for 2018 to 2019

[DoninGA]

Once the tax return has been filed it cannot be changed.  If you need to make changes you will have to amend the 2019 tax return.

An amended tax return, Form 1040X, can only be printed, signed, dated and mailed by you to the IRS, it cannot be e-filed. The IRS will take up to 4 months to process the amended tax return. Wait until you have received the tax refund or the taxes owed have been paid and processed by the IRS before amending the tax return.

See this TurvrboTax support FAQ for amending a 2019 tax return - https://ttlc.intuit.com/community/tax-topics/help/how-do-i-amend-a-2019-return-in-turbotax/01/123845...

[Critter-3]

If you applied the 2018 to the 2019 return and you failed to put that on the 2019 return AND  the return has been efiled successfully OR mailed it in already then  you MUST wait for the IRS to process your return ... this is an error they usually catch automatically.    If they don't only then may you amend your return.