I file my 1040 but I should have filed a 1040 AR what can I do. I am sorry a 1040 SR?

If you were 65 or older at the end of 2023 the software will print your return out on a 1040SR.  The From 1040 and Form 1040SR are identical.  All the lines and calculations are exactly the same. The only difference is that the 1040SR has larger print.   There is no reason to stress over the use of 1040 vs. 1040SR.

It's OK to file a form 1040, instead of a form 1040-SR, as they both use the same schedules.

See this IRS document.

In the Online version it will probably show the regular 1040 on the screen but if you print it out or save the pdf it will be the 1040-SR.

The 1040SR is EXACTLY the same as the regular 1040 just larger type so it goes on 3 pages with the Standard Deduction chart on page 4. But it has the same line numbers. You automatically get the SR if you or your spouse is 65 or older.  It doesn't  matter which one you file.