I paid my taxes for 2019 but I used the wrong coupon my payment ended up going to Estimated Taxes for 2020. How do I get my payment to apply to 2019 Taxes?

I don't know if you can.  Ask the IRS.  You might still have to pay the tax due and wait to get credit for the payments on next year's return.

I got through to the IRS had to wait an hour. but the representative moved it over to my current tax bill.

Great!  Thanks for letting us know you can ask them.