2020 IRA Contributions for 2019

I read you can contribute to your 2019 IRA up until July 15 2020.  But Turbo Tax has an option for 2020 contributions.  It doesn't seem to benefit me if I increase that contribution. Meaning no decrease in tax owed.  However, any addition under 2019 IRA contributions does decrease my "tax owed."  Can I just add all my contributions from 2019 and 2020 under the 2019 contribution option?