I had the Affordable Care Act for 9 months of the year. I need to edit the Modified AGI on Form 8692. Online won't allow me to edit it.

You can't edit the MAGI.  Your MAGI is the amount you actually received during the entire year. Form 8962 is a reconciliation of what you told them you would earn during the year with what you actually received.  If you receive more than you told them, you will generally have to pay back some or all of the credit. The credit is based on your income for the year, it is not calculated per month.  

This means, even if you earned $10,000 from January to November, then somehow earned $50,000 in December, your credit is based off of the $60,000 in income.  The $10,000 is not relevant on a monthly basis, it is only factored as part of the entire income for the year. 

The ONLY way you could change your AGI is if you left out a W2 or added one that you shouldn't have.  IF this is the case, then you can change your return if you have not yet filed by going back to the income section and click wages and income>>edit next to the W2>>Add a W2.

If you did file, then you will need to Amend Your Return to include any additional W-2 or remove any that you should not have entered. 

Note: Your W2's must be entered exactly as they are, only enter the ones for 2022 and enter all of them that you have. If you have already done so, then there is nothing you can do to change your AGI.  

(Edited 3/1/2023 @ 5:49AM PST) @deadhead626