If you are signed onto your account, accessing the 2020 online tax return and working on the 2020 tax return then the Tax Tools link is on the left hand column on the program screen, provided that you have not minimized the screen so much so the left hand column is no longer visible. Or you are using some tiny mobile phone screen to do your tax return.
If you do not see the left side column, click on the 3 horizontal lines at the top left corner of the online program screen.
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.