Are you using the Online browser version or the Desktop program on your computer? After you open the file you do not go to Wages & Income. First you go to Federal > Other Tax Situations > Other Tax Forms > Amend a Return.
So first take out the interest you added and any changes you made and put your return back to the way it was when you filed. Then go to Amend a Return to start the amended return. The refund/tax due monitors should reset to zero. Then you enter the missing interest.
Hope this helps.
