"Your spouse's net income for the year is required to properly calculate your tax return" I entered an incorrect amount; how do I go back and fix it? I cannot find it any more..

There was an error "Your spouse's net income for the year is required to properly calculate your tax return".   I entered an incorrect amount by mistake; how do I go back and fix it? I cannot find it any more..  I've searched every where.  My wife passed away last year and I am filling as a widow.

Thanks!