As long as your extension request has been accepted and not rejected by the IRS, you will not need to submit a different form. Even if you checked the box and it didn't apply. The extension give a time to file of October 16, 2023.
You do not need to correct the form- if you are outside the U.S. you get an automatic 2 month extension, the 4868 extends it four additional months so the due date is the same as if you were in the U.S. (October 16, 2023). This is an automatic extension so the reason is not required.
Thanks MaryK4:
I am in the country. I checked the box 8 incorrectly. Do I need to file another 4868 without the box 8 checked?
There is some chat about another extension form 2350 which in my case doesn't apply.
Thanks,
As long as your extension request has been accepted and not rejected by the IRS, you will not need to submit a different form. Even if you checked the box and it didn't apply. The extension give a time to file of October 16, 2023.
Being out of the country gives you two additional months to file and pay. Still you will pay interest if paying after April 18th.
If you were not out of the country , pay all tax by April 18th.