Was un able at time of fileing yo verify third stimulus payment so selected as a credit later found verification How can I get this fixed?

No do not amend.   You just have to wait for the IRS to fix your mistake.   By answering incorrectly about the stimulus amount you received you put an amount on line 30 of your Form 1040.   The IRS checks that line.  They know how much they sent to you.   They will reduce your refund by that amount.   This will delay your refund so expect a wait.

The IRS knows that you were sent the 3rd stimulus payment so they will adjust your tax return accordingly by removing the Recovery Rebate Credit from your tax return thereby reducing your federal tax refund and/or increasing the federal taxes owed.  The IRS will be sending you a letter in the mail explaining the changes that were made.

You do not need to amend the 2021 tax return.