Amending a return for adding a Roth IRA for 2020

i filed my taxes already and got my refund, but even since my divorce I was meaning to startup a Roth IRA to help with my retirement plans since my 401K took a 50% hit due to giving away half.  I'm over 50 so wanted to use that max of 7000.

 

anyway... I forgot to do it again but filed already.  I heard that I can still contribute as if it was 2020 until May 17 2021... but when I go in to file an amended return it tells me nothing is different even though I've entered the amounts.
I seem to see mention that it's not required to even enter it on your taxes

https://ttlc.intuit.com/community/retirement/discussion/if-i-already-filed-my-taxes-and-want-to-make...

but I would want to have it recorded somewhere that I've done this in 2020 and been told to have a tax professional do it.
In particular as i plan to use it in investing so that it is properly tracked and at least make it print somewhere as doing the amended return does not show the value.

 

-James