Forgot to adjust my ltrading losses from 2017

Hi There:

Sorry to say, but it's unclear what type of losses that you are referring to? Considering the date of 2017, it feels like a capital loss carryover issue, but then again it could be something else. Please try to repost  and specify the exact type of loss, year of change and amount of change. If you can't repost then Turbo Tax Online is always available.

Thank you for posting this question,  you can do this by filing an amendment.   However, the IRS may deny you claim for this credit.  The IRS States on their website "Generally, for a credit or refund, you must file Form 1040-X within 3 years (including extensions) after the date you filed your original return or within 2 years after the date you paid the tax, whichever is later."  Either way amending now is worth a try.   This will allow you losses to be carried forward.  https://www.irs.gov/instructions/i1040x