My preliminary 2020 payable amount does not make any sense to me. Is there anyway to compare the 2020 with 2019? How else to trouble shoot the data?

Only by printing each year out and comparing them line by line.  But 2020 program is not fully ready yet, there will be many updates to come.

Many portions of the 2020 TurboTax program have not been finalized due the IRS not yet completing many 2020 Forms, Schedules and instructions.

You can view your Form 1040 at any time. Click on Tax Tools on the left side of the screen. Click on Tools. Click on View Tax Summary. Click on Preview my 1040 on the left side of the screen.

If you signed onto the 2020 TurboTax online account using the same User ID that was used for the 2019 online account -

Click on Tax Home on the left side of the online program screen.

Scroll down to the bottom of the screen and on the section Your tax returns & documents click on Show.  Click on 2019 and Click on Download/print return (PDF)