You should not amend until the first return has fully processed and you get the first refund or your tax due payment has cleared.
You can find Amend under
Federal Taxes or Personal (for Home & Business)
Other Tax Situations
How to Amend this year
https://ttlc.intuit.com/turbotax-support/en-us/help-article/tax-return/amend-federal-tax-return-curr...
